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Western Journal of Emergency Medicine

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Volume 27, Supplement, November 2026

Open Access at www.westjem.com

ISSN 1936-900X

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health Indexed in MEDLINE

VOLUME 27, Supplement, November 2026

Special Issue on Climate Change

PAGES 1-185

A Peer-Reviewed, International Professional Journal

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Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded Andrew W. Phillips, MD, Associate Editor DHR Health-Edinburg, Texas Soheil Saadat, MD, PhD, MPH, Deputy Editor University of California, Irvine School of Medicine Irvine, California Edward Michelson, MD, Associate Editor Texas Tech University- El Paso, Texas

Mark I. Langdorf, MD, MHPE, Editor-in-Chief University of California, Irvine School of MedicineIrvine, California Shahram Lotfipour, MD, MPH, Managing Editor Eisenhower Medical Center University of California, Irvine School of MedicineIrvine, California

Dan Mayer, MD, Associate Editor Retired from Albany Medical College- Niskayuna, New York Gayle Galletta, MD, Associate Editor University of Massachusetts Medical SchoolWorcester, Massachusetts Yanina Purim-Shem-Tov, MD, MS, Associate Editor Rush University Medical Center-Chicago, Illinois

Gary Gaddis, MD, PhD, Associate Editor University of California, Irvine School of Medicine- Irvine, California Rick A. McPheeters, DO, Associate Editor Kern Medical- Bakersfield, California R. Gentry Wilkerson, MD, Associate Editor University of Maryland

Quincy Tran, MD, Deputy Editor University of Maryland School of Medicine- Baltimore, Maryland Brian Yun, MD, MPH, MBA, Associate Editor Boston Medical Center-Boston, Massachusetts Michael Pulia, MD, PhD, Associate Editor University of Wisconsins Hospitals and Clinics- Madison, Wisconsin Patrick Joseph Maher, MD, MS, Associate Editor Ichan School of Medicine at Mount Sinai- New York, New York Donna Mendez, MD, EdD, Associate Editor University of Texas-Houston/McGovern Medical School- Houston Texas Danya Khoujah, MBBS, Associate Editor University of Maryland School of Medicine- Baltimore, Maryland

Section Editors

Dell Simmons, MD Geisinger Health

Julian Mapp, MD University of Texas, San Antonio

Taylor Burkholder, MD, MPH Keck School of Medicine of USC

Bradford Brobin, MD, MBA Chicago Medical School

Disaster Medicine

Shira A. Schlesinger, MD, MPH Harbor-UCLA Medical Center

Christopher Greene, MD, MPH University of Alabama

Tiffany Abramson, MD University of Southern California

Chris Mills, MD, MPH Santa Clara Valley Medical Center

Jason Pickett, MD University of Utah Health

Shada Rouhani, MD Brigham and Women’s Hospital

Geriatrics

Legal Medicine

Luna Ragsdale, MD, MPH Duke University

Statistics and Methodology

Behavioral Emergencies Marc L. Martel, MD Hennepin County Medical Center Ryan Ley, MD, MBA Hennepin County Medical Center

Cardiac Care

Andrew Milsten, MD, MS UMass Chan Medical Center John Broach, MD, MPH, MBA, FACEP University of Massachusetts Medical School Christopher Kang, MD Madigan Army Medical Center

Sam S. Torbati, MD Cedars-Sinai Medical Center

Scott Goldstein, MD Temple Health

Rohit Menon, MD University of Maryland

Education

Elif Yucebay, MD Rush University Medical Center Mary McLean, MD AdventHealth

Stephen Meldon, MD Cleveland Clinic

Danya Khoujah, MBBS University of Maryland School of Medicine Jeffrey Druck, MD University of Colorado

Gary Gaddis, MD, PhD University of California, Irvine School of Medicine- Irvine, California

Cameron Hanson, MD The University of Kansas Medical Center

Clinical Practice

Casey Clements, MD, PhD Mayo Clinic Murat Cetin, MD Behçet Uz Child Disease and Pediatric Surgery Training and Research Hospital Carmine Nasta, MD Università degli Studi della Campania “Luigi Vanvitelli” David Thompson, MD University of California, San Francisco Tom Benzoni, DO Des Moines University of Medicine and Health Sciences

Shu B. Chan, MD, MS Resurrection Medical Center

Health Equity

Asit Misra, MD University of Miami

Climate Change

Melanie S. Heniff, MD, JD Indiana University School of Medicine

Cortlyn W. Brown, MD Carolinas Medical Center

Soheil Saadat, MD, MPH, PhD University of California, Irvine

Faith Quenzer, DO, MPH Temecula Valley Hospital San Ysidro Health Center

James A. Meltzer, MD, MS Albert Einstein College of Medicine

Victor Cisneros, MD, MPH Eisenhower Health

Monica Gaddis, PhD University of Missouri, Kansas City School of Medicine

Gary Johnson, MD Upstate Medical University

Sara Heinert, PhD, MPH Rutgers University

Emad Awad, PhD University of Utah Health

Brian J. Yun, MD, MBA, MPH Harvard Medical School

Naomi George, MD, MPH University of Mexico

Musculoskeletal

Laura Walker, MD Mayo Clinic

Sarah Aly, DO Yale School of Medicine

León D. Sánchez, MD, MPH Beth Israel Deaconess Medical Center

Lauren Walter, MD University of Alabama

Robert Derlet, MD Founding Editor, California Journal of Emergency Medicine University of California, Davis

Infectious Disease

ED Administration, Quality, Safety

Juan F. Acosta, DO, MS NYU Langone Hospital

Neurosciences

Rick Lucarelli, MD Medical City Dallas Hospital William D. Whetstone, MD University of California, San Francisco

Elissa Schechter-Perkins, MD, MPH Boston University School of Medicine

Tehreem Rehman, MD, MPH, MBA Beth Israel Deaconess Medical Center

Ioannis Koutroulis, MD, MBA, PhD George Washington University School of Medicine and Health Sciences

Anthony Rosania, MD, MHA, MSHI Rutgers University

Stephen Liang, MD, MPHS Washington University School of Medicine

Joseph Shiber, MD University of Florida-College of Medicine

Neil Dasgupta, MD, FACEP, FAAEM Nassau University Medical Center

Injury Prevention

David Page, MD University of Alabama

Emergency Medical Services

Critical Care

Christopher “Kit” Tainter, MD University of California, San Diego

Antonio Esquinas, MD, PhD, FCCP, FNIV Hospital Morales Meseguer

Mark Faul, PhD, MA Centers for Disease Control and Prevention

Daniel Joseph, MD Yale University

Wirachin Hoonpongsimanont, MD, MSBATS Eisenhower Medical Center

Joshua B. Gaither, MD University of Arizona, Tuscon

International Medicine

Heather A. Brown, MD, MPH Prisma Health Richland

Antonio Siniscalchi, MD Annunziata Hospital, Cosenza, Italy

Pediatric Emergency Medicine

Muhammad Waseem, MD Lincoln Medical & Mental Health Center Cristina M. Zeretzke-Bien, MD University of Florida Jabeen Fayyaz, MD The Hospital for Sick Children Reshvinder Dhillon, MD University of Southern Alabama Kathleen Stephanos, MD University of Mississippi Medical Center

Official Journal of the California Chapter of the American College of Emergency Physicians, the American College of Osteopathic Emergency Physicians, the California Chapter of the American Academy of Emergency Medicine, and Official International Journal of the World Academic Council of Emergency Medicine (WACEM)

World Academic Council of Emergency Medicine

Available in MEDLINE, PubMed, PubMed Central, CINAHL, SCOPUS, Google Scholar, eScholarship, Melvyl, DOAJ, EBSCO, EMBASE, Medscape, HINARI, and MDLinx Emergency Med. Members of OASPA. Editorial and Publishing Office: WestJEM/Depatment of Emergency Medicine, UC Irvine Health, 3800 W. Chapman Ave. Suite 3200, Orange, CA 92868, USA Office: 1-714-456-6389; Email: Editor@westjem.org

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded Section Editors (Continued) Public Health

John Ashurst, DO, MSc, EdD Lehigh Valley Health Network Tony Zitek, MD Kendall Regional Medical Center

Howard Greller, MD Rutgers University

Chris Baker, MD University of California, San Francisco

Robert Allen, MD Keck Medicine of USC

Trauma

Shane Summers, MD Brooke Army Medical Center

Women’s Health

Pierre Borczuk, MD Massachusetts General Hospital/Havard Medical School

Erik S. Anderson, MD Alameda Health System-Highland Hospital

Lesley Osborn, MD University of Colorado Anschutz Medical Campus

Toxicology

Ultrasound

Jeffrey R. Suchard, MD University of California, Irvine

Robert R. Ehrman, MD, MS Wayne State University Ryan C. Gibbons, MD Temple Health

J. Matthew Fields, MD Thomas Jefferson University

Elisabeth Calhoun, MD, MPH Trinity Health Marianne Haughtey, MD Zucker School of Medicne at Hofstra/Northwell

World Academic Council of Emergency Medicine

Western Journal of Emergency Medicine

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded

Editorial Board Amin A. Kazzi, MD, MAAEM The American University of Beirut, Beirut, Lebanon Anwar Al-Awadhi, MD Mubarak Al-Kabeer Hospital, Jabriya, Kuwait Arif A. Cevik, MD United Arab Emirates University College of Medicine and Health Sciences, Al Ain, United Arab Emirates Brent King, MD, MMM University of Texas, Houston Daniel J. Dire, MD University of Texas Health Sciences Center San Antonio

Edward Panacek, MD, MPH University of South Alabama

Leslie Zun, MD, MBA Chicago Medical School

Scott Rudkin, MD, MBA University of California, Irvine

Hoon Chin Steven Lim, MBBS, MRCSEd Changi General Hospital

Linda S. Murphy, MLIS University of California, Irvine School of Medicine Librarian

Scott Zeller, MD University of California, Riverside

Gayle Galleta, MD Sørlandet Sykehus HF, Akershus Universitetssykehus, Lorenskog, Norway

Pablo Aguilera Fuenzalida, MD Pontificia Universidad Catolica de Chile, Región Metropolitana, Chile

Jaqueline Le, MD Desert Regional Medical Center

Peter A. Bell, DO, MBA Baptist Health Sciences University

Jeffrey Love, MD The George Washington University School of Medicine and Health Sciences

Peter Sokolove, MD University of California, San Francisco

Jonathan Olshaker, MD Boston University

Rachel A. Lindor, MD, JD Mayo Clinic

David F.M. Brown, MD Massachusetts General Hospital/ Harvard Medical School

Katsuhiro Kanemaru, MD University of Miyazaki Hospital, Miyazaki, Japan

Robert M. Rodriguez, MD University of California, Riverside

Douglas Ander, MD Emory University

Kenneth V. Iserson, MD, MBA University of Arizona, Tucson

Edward Michelson, MD Texas Tech University

Khrongwong Musikatavorn, MD King Chulalongkorn Memorial Hospital, Chulalongkorn University, Bangkok, Thailand

Elena Lopez-Gusman, JD California ACEP American College of Emergency Physicians Amanda Mahan, Executive Director American College of Osteopathic Emergency Physicians

Wirachin Hoonpongsimanont, MD, MSBATS Siriraj Hospital, Mahidol University, Bangkok, Thailand

Robert Suter, DO, MHA UT Southwestern Medical Center Robert W. Derlet, MD University of California, Davis Samuel J. Stratton, MD, MPH Orange County, CA, EMS Agency

Editorial Staff

Advisory Board Kimberly Ang, MBA UC Irvine Health School of Medicine

Terry Mulligan, DO, MPH, FIFEM ACEP Ambassador to the Netherlands Society of Emergency Physicians

Peter A. Bell, DO, MBA American College of Osteopathic Emergency Physicians Baptist Health Science University Robert Suter, DO, MHA American College of Osteopathic Emergency Physicians UT Southwestern Medical Center

John B. Christensen, MD California Chapter Division of AAEM

Shahram Lotfipour, MD, MPH Eisenhower Medical Center UC Irvine Health School of Medicine

Randy Young, MD California ACEP American College of Emergency Physicians

Brian Potts, MD, MBA California Chapter Division of AAEM Alta Bates Summit-Berkeley Campus

Luke Garcia, BS Executive Editorial Director

Cassandra Saucedo, MS Executive Publishing Director

Acacia Jang, BS WestJEM Editorial Director

Isabella Choi, BS WestJEM Publishing Director

Isabella Cao, BS CPC-EM Editorial Director

Annie Zhang, BS WestJEM Associate Publishing Director

Stephanie Burmeister, MLIS WestJEM Staff Liaison

Omid Haghkhah, BS CPC-EM Publishing Director June Casey, BA Copy Editor

Mark I. Langdorf, MD, MHPE UC Irvine Health School of Medicine Jorge Fernandez, MD California ACEP American College of Emergency Physicians University of California, San Diego

World Academic Council of Emergency Medicine

Available in MEDLINE, PubMed, PubMed Central, Europe PubMed Central, PubMed Central Canada, CINAHL, SCOPUS, Google Scholar, eScholarship, Melvyl, DOAJ, EBSCO, EMBASE, Medscape, HINARI, and MDLinx Emergency Med. Members of OASPA. Editorial and Publishing Office: WestJEM/Depatment of Emergency Medicine, UC Irvine Health, 3800 W. Chapman Ave. Suite 3200, Orange, CA 92868, USA Email: Editor@westjem.org

Western Journal of Emergency Medicine

iii

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded

JOURNAL FOCUS Emergency medicine is a specialty which closely reflects societal challenges and consequences of public policy decisions. The emergency department specifically deals with social injustice, health and economic disparities, violence, substance abuse, and disaster preparedness and response. This journal focuses on how emergency care affects the health of the community and population, and conversely, how these societal challenges affect the composition of the patient population who seek care in the emergency department. The development of better systems to provide emergency care, including technology solutions, is critical to enhancing population health.

Table of Contents 1

Introducing the Climate Change Special Issue G Gaddis, S Lotfipour

Association of Heat Index and Patient Presentation Rate at a Stadium J Wolin, Daniel W, John S, Eric Q, David E, Humaira A, David L, MS Friedman

Influence of Daily Meteorological Changes on Stroke Incidence Across the United States RL Ung, JS Lubin

Emergency Medicine at the Frontline of Climate Change: The Role of Geographic Information Systems T Surapaneni, A Patrikakou, A Faka, L Grant, A Ulrich, D Tsiftsis, E Reid

Association of Rising Ambient Temperatures with Increased Violence Worldwide: Systematic Review and Meta-Analysis V Chauhan, S Thakur, S Galwankar, S Temple

Impact of Daily Maximum Temperature on Emergency Department Arrivals and Acuity Levels C Giudice, NJ Arisco, Z Lu, B Stenson, C Dresser

Emergency Department Management of Acute Heatstroke: A Retrospective Analysis from Phoenix, Arizona J Stowell, P Pugsley, M McElhinny, G Comp, J Pearlmutter, M Akhter, D Sklar

“Predictive Factors and Nomogram for 30-Day Mortality in Heatstroke Patients: A Retrospective Cohort Study” JR Stowell, G Comp, P Pugsley, M McElhinny, M Akhter

Effect of Ice Consistency and Sodium Chloride Additives on Cooling Speed and Final Temperature for Cold Water–Ice Immersion in Heat Stroke AJ Goldmann, B Yavari, DP Sklar

12-Year Case Series of Patients with Heat Illness from an Urban Hospital System in the American Southwest M McElhinny, L Garr, T Chen, B Garcia, B Bhattarai, L Kraynov, G Comp

Impact of Emergency Department Intravenous Fluid Conservation Strategies During a National Shortage: A Multi-Site Retrospective Study H Moreira, R McCormack, C Sorensen, B Mallory

US Emergency Department Use and Operations Amid Natural Disasters: A Narrative Review A Patel, AA Foster, EY Popovsky, A Fawcett, JA Hoffmann

Policies for peer review, author instructions, conflicts of interest and human and animal subjects protections can be found online at www.westjem.com. Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded

Table of Contents continued 80

Selected Impacts of Urban Heat Islands on Emergency Medical Services Utilization in Rhode Island K Moretti, Y Liang, JM Nicklas, B Fox-Kemper, C Decerbo, H Torabzadeh, CH Schmid, A Aluisio

Creating and Maintaining a “Climate-Smart” Emergency Department: A Scoping Review of Current Progress and Future Potential L Moujaes, K Iuliucci

Implementing a Climate Health Education Curriculum for Emergency Medicine Trainees and Faculty E Lewis, CM Smalley, M Kostura

103

Reducing Waste: Instrument Recycling in the Emergency Department EH Chen, K Taguma, N Addo, JK Quinn

107

Climate Change and Emergency Medicine: A Scoping Review Across Emergency Medicine Subspecialties L Moujaes, K Iuliucci, S Wheat

116

Mechanisms and Intervention Strategies for Heat Stroke-Associated Myocardial Dysfunction: A Narrative Review Y Zhuang, XH Zhuang, XY Zhang, DC Wang, Y Yang

124

Cultivating Environmentally Sustainable Emergency Departments with GreenED JL Wood, A Robertson, T Spruell, Z Steley

132

Evaluating the Impact of a Sustainability Education Intervention on Emergency Medicine Residents AD Ashkezari, C Bogdani, X Huang, M Gindi

140

Climate Change and Heat-related Illness in Older Adults: Implications for Emergency Medicine EL Simon, K Watkins, S Meldon

145

Implementation Science to Advance Equity in Climate-Driven Disaster Response W Mundo, J Ryder, M Ross, CB Bills, LS Newman, J Lemery

155

Sustainability in Quality Improvement: Outcomes of a Novel Pediatric Virtual Urgent Care in Ontario, Canada E Lim, J Strychowsky, AC Gunz, S Belisle

163

Impact of Increasing Ambient Temperatures on Emergency Department Trauma Presentations at a Level I Trauma Center GE Mosley, M Arnold, B Sharma, JWhittington, G Jara-Almonte

174

Partial Immersion Using Body Bags for Exertional Hyperthermia: A Randomized Crossover Study D Zashin, X Zhao, L Vela, E Parke, R Ylanan, BP McDermott

181

Higher Intensity Quality Improvement Campaign Yields Greater Reduction in Medical Glove Use: The “Gloves Off!” Campaign LH Foong, M Knox, A Malik, W Hird

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

Indexed in MEDLINE, PubMed, and Clarivate Web of Science, Science Citation Index Expanded This open access publication would not be possible without the generous and continual financial support of our society sponsors, department and chapter subscribers.

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Western Journal of Emergency Medicine

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine: Integrating Emergency Care with Population Health

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Western Journal of Emergency Medicine

vii

Volume 27, Supplement: November 2026

Call for Reviewers!

Please send your CV and letter of interest to editor@westjem.org

Expert Commentary

Introducing the Climate Change Special Issue Gary Gaddis, MD, PhD* Shahram Lotfipour, MD, MPH*†

*University of California, Irvine School of Medicine, Department of Emergency Medicine, Orange, California, Rancho Mirage, California † Eisenhower Medical Center, Department of Emergency Medicine,

Section Editor: N/A Submission history: Submitted June 30, 2026; Accepted July 5, 2026 Electronically published September 24, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.66424

[West J Emerg Med. 2026;27(6.1)1–2.]

industry’s net output of greenhouse gases. Subsequently, at the June 2026 Annual Meeting of the House of Delegates of the AMA, Resolution 404-A-26 was adopted, adding to the impetus to make climate-conscious resources more available to clinicians. Its “Resolved” clauses include the following: • RESOLVED, that our American Medical Association support compiling and maintaining a resource for US physicians, focused on education physicians and other healthcare professionals about the health impacts of climate change and the role of the healthcare sector in contributing to greenhouse gas emissions; and be it further • RESOLVED, that our AMA support providing practical, evidence-based recommendations for reducing the environmental footprint of clinical practices and healthcare systems; and be it further • RESOLVED, that our AMA support offering resources and tools to support physicians in advocating for environmentally sustainable policies and practices within their organization and communities; and be it further • RESOLVED, that our AMA facilitate collaboration and sharing of best practices among healthcare professionals and institutions committed to addressing climate change and promoting sustainability.

The Western Journal of Emergency Medicine (WestJEM) is pleased to present its Climate Change Special Issue. These 23 manuscripts explore how choices in emergency department (ED) operations and processes affect climate change drivers, including greenhouse gas emissions. This special issue grew out of my suggestion to Editor-in-Chief Mark Langdorf, MD, MHPE, that the journal focus on climate issues, similar to its periodic special issues on medical education. Several factors prompted this suggestion: • In the United States, the healthcare industry contributes about 8.5% of all greenhouse gases produced in our economy.1 • Choices in emergency care delivery directly influence greenhouse gas production. When I first proposed this issue, I had recently served as Decision Editor for a WestJEM manuscript quantifying how the use of reusable, sterilizable oximeter probes in the ED could favorably reduce these emissions.2 • When the journal issued its “Call for Papers,” the American Medical Association (AMA) had already adopted at least 12 policies addressing climate change.3 These policies include the following: o Policy D-135.966 (last modified in 2024) declares climate change to be a public health crisis. It further states, the AMA “will protect patients by advocating for policies that:  Limit global warming to no more than 1.5 degrees Celsius  Reduce US greenhouse gas emissions aimed at a 50 percent reduction in emissions by 2030 and carbon neutrality by 2050.” o Policy D-440-912 (last modified in 2023) advocates for a “net zero” carbon society by 2050. • Increased implementation of “telemedicine” since the onset of the COVID-19 pandemic has had a small but measurable and salutatory effect upon the healthcare Volume 27, Supplement: November 2026

We hope this issue will support the AMA’s goals within our emergency medicine community. Mitigating healthcare industry greenhouse gas emissions to eventually achieve carbon neutrality will require multiple strategies rather than a single “magic bullet.” However, important incremental steps are already uuderway. For example, the University of California, Irvine, recently opened the first “all-electric” hospital in the United States.4 Substantial, and perhaps surprising, progress is also occurring in emergency services delivery: • Great Britain’s National Health Service (NHS) committed to a “net-zero” carbon footprint by 2040, 1

Western Journal of Emergency Medicine

Introducing the Climate Change Special Issue

Gaddis et al.

followed by a net-zero target for its wider supply chain and influenced emissions by 2045.6 As part of this initiative, the NHS is systematically phasing out emergency medical service (EMS) vehicles powered by fossil fuels and replacing decommissioned units with zero-emission models.5 o While both Great Britain and the US have extensive rural areas, the British advantage lies in the fact that the NHS operates all ambulance services, compared with the “patchwork” of agencies operating in the US. • Nonetheless, this EMS vehicle goal is being rapidly met within some British EMS systems, surprisingly in areas that are not densely populated metropolitan centers like Central London. o The NHS Hillingdon Hospitals, located west of London and north of Heathrow Airport, have already transitioned their EMS vehicles to 100% electrically powered.6 o In Yorkshire, a largely rural northern area of the United Kingdom that also includes the cities of York and Leeds, 35 of a planned 108 renewably powered ambulances are already in service.7 WestJEM’s attention to climate change is not unique. As a regular reader of the Journal of the American Medical Association, I know that as of June 2026, JAMA had published at least 20 climate-related articles and news items. So, in closing, when viewed from the perspective of 2030 or even 2050, this “Special Issue” will hopefully be viewed as a vital first step taken by our emergency medicine community toward reducing our collective greenhouse gas production. As the proverb states, “A journey of 1000 miles begins with but a single step.” In that spirit, we present our Special Climate Change Issue.

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Gaddis et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/ REFERENCES 1. Commonwealth Fund. How the U.S. health care system contributes to climate change. 2022. Available at: https://www.commonwealthfund. org/publications/explainer/2022/apr/how-us-health-care-systemcontributes-climate-change. Accessed March 15, 2024. 2. Duffy J, et al. Sustainable purchasing practices: A comparison of single-use and reusable pulse oximeters in the emergency department. West J Emerg Med. 2023;24(6):1034-42. 3. American Medical Association. AMA Policy Finder: Climate Change. Available at: https://policysearch.ama-assn.org/policyfinder/search/ climate%20change/relevant/1/. Accessed September 17, 2025. 4. UCI Health. UCI Health making history with nation’s first all-electric acute care hospital. 2025. Available at: https://www.ucihealth.org/ about-us/news/2025/06/all-electric-hospital. Accessed September 17, 2025. 5. NHS England. Delivering a “Net Zero” National Health Service. 2022. Available at: https://www.england.nhs.uk/greenernhs/wp-content/ uploads/sites/51/2022/07/B1728-delivering-a-net-zero-nhs-july-2022. pdf. Accessed March 15, 2024. 6. The Hillingdon Hospitals NHS Foundation Trust. UK first as all ambulances go electric. 2025. Available at: https://thh.nhs.uk/newsevents/uk-first-as-all-patient-ambulances-go-electric-2403/. Accessed September 17, 2025. 7. Yorkshire Ambulance Service NHS Foundation Trust. Yorkshire Ambulance Service unveils new eco-friendly vehicles. 2025. Available at: https://www.yas.nhs.uk/news/media-releases/media-

Address for Correspondence: Gary M. Gaddis, MD, PhD, FIFEM MAAEM; Guest Editor; WestJEM Climate Change Special Issue. Email: garymgaddis86@gmail.com.

Western Journal of Emergency Medicine

releases-2025/yorkshire-ambulance-service-unveils-new-ecofriendly-vehicles/. Accessed September 17, 2025.

Volume 27, Supplement: November 2026

Original Research

Association of Heat Index and Patient Presentation Rate at a Stadium Jennifer Wolin, MD* Daniel Wolf, DO* John Su, MD† Eric Quinn, MD* David Eng, MD* Humaira Ali, DO* David Lobel, MD* Matt Friedman, MD*

*Maimonides Medical Center, Department of Emergency Medicine, Brooklyn, New York † Stanford Medicine, Department of Emergency Medicine, Stanford, California

Section Editor: Emily Sbiroli, MD Submission history: Submitted August 18, 2024; Revision received February 5, 2025; Accepted February 11, 2025 Electronically published May 19, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.21222

Introduction: A mass gathering is defined as an event that has the potential to strain the resources of the local health system. An onsite physician for mass gatherings can mitigate the strain on the local health infrastructure. One factor affecting onsite medical usage and patient presentation rates is the heat index, which is a calculated value of perceived heat exposure that combines air temperature and relative humidity. In this study we asked whether there was a positive association between heat index and patient presentation rates for onsite medical care at a bounded (large event in an enclosed location) professional stadium sporting event. We hypothesized that a positive correlation exists between these two variables and assess whether it might surpass current onsite resources. Methods: We performed a prospective observational study with patients seeking medical care at a baseball stadium in a large northeastern city in the United States. The onsite physician collected information on patients who presented during games held at the stadium. Data on game attendance, temperature in degrees Fahrenheit (F), humidity, and heat index were collected using government and professional organization websites. We assessed the correlation between heat index and patient presentation rate with the Pearson product-moment correlation (PPMC) per 100,000 attendees at the game. Results: A total of 81 baseball games occurred at the studied stadium from April–September 2023, with eight games excluded due to incomplete data. The heat index ranged from 46°F to 91°F, with a mean (± SD) of 70.8°F (± 10.4°F). The number of patients varied from 0-5 per game, with a mean of 1.92 (± 1.13), and stadium attendance ranged from 25,007 to 47,295, with a mean of 40,824. The patient presentation rate per 100,000 in attendance was 5.04 (± 2.13). The PPMC was calculated to be 0.37 (P < .01), indicating a positive correlation between heat index and patient presentation rates. The most common reasons for seeking medical care were lightheadedness and musculoskeletal complaints. Conclusion: In this study we found that the heat index was moderately associated with higher patient presentation rates at bounded mass gathering baseball events. No additional resources were needed, but this correlation could aid future event medical planning efforts as the climate continues to evolve. [West J Emerg Med. 2026;27(6.1)3–9.]

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Western Journal of Emergency Medicine

Association of Heat Index and Patient Presentation Rate at a Bounded Mass-gathering Event INTRODUCTION A mass gathering is defined as an event that has the potential to strain the resources of the local health system or community.1-4 Understanding patient presentation rates and etiologies at mass gatherings is essential for maximizing the efficient use of resources and onsite health services, and for activating ambulance services. Effective preparedness for mass gatherings can minimize delays to definitive care and alleviate the burden on local hospitals’ resources that would otherwise result from the mass gathering by staffing and planning for predictable health risks, such as heat-related illness. 5-8 Furthermore, data collected from onsite medical care can inform public health surveillance efforts, enabling local emergency departments and 9-1-1 systems to anticipate resource needs and coordinate mutual aid staffing, especially in similarly sized events that may not have onsite medical staffing. Some states have legislated certain regulatory criteria for providing healthcare services at such events to ensure sufficient mass-gathering medical care. In New York State, for example, any event with greater than 5,000 attendees requires a physician to be available within 15 minutes, while events with greater than 30,000 attendees require a physician onsite.9 Event physicians can enhance the medical care given by prehospital personnel by providing on-scene medical direction and offering independent and complex medical decisionmaking, including the ability to return participants safely to the event without unnecessary transport.10 For those who may require medical evaluation, the onsite physician can determine the most optimal transport mode or even consent for an “against medical advice” decision, if appropriate.11 This allows for optimizing transport resources and minimizing the impact on local ambulance services and emergency departments.10 Event physicians may also have prehospital training, encompassing mass casualty triage and familiarity with the incident command system, to effectively manage a sudden surge of patients.11 The exact role also varies based on the event and distance to definitive care. Events located hours from the closest hospital require more extensive onsite medical care to return participants to the event and conserve medical transport resources due to long turn-around times. Most mass gathering literature defines three domains impacting healthcare at events.12 These include biomedical (spectator demographics and health status), psychosocial (crowd behavior, culture, reason for attendance), and environmental (characteristics of venue, weather, presence of drugs or alcohol). The biomedical domain includes the principles of patient presentation rates (PPR) and transfer to hospital rates (TTHR).13-14 The PPR provides insight into the utilization of onsite health services and refers to the number of attendees who present requesting onsite medical care, while TTHR provides information on prehospital ambulance transports out of the venue. On occasion, patients may refuse ambulance services and elect to self-transfer. This is known as the self-transfer to hospital rate (STHR), which is defined as Western Journal of Emergency Medicine

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Population Health Research Capsule What do we already know about this issue? Heat increases medical needs at mass gatherings, but data on heat index and its impact on patient presentation rates (PPR) is limited. What was the research question? Is there a positive association between heat index and PPR at a bounded professional baseball stadium event? What was the major finding of the study? For every 10°F rise in heat index, PPR rates increased by 1.46 per 100,000 attendees (r = 0.37, P < .01). How does this improve population health? These findings help optimize medical staffing at bounded mass gatherings, ensuring sufficient resources as climate change increases heat-related health risks.

the number of patients who present for medical attention and elect to go to a hospital by private means. The total number of patients who present to local hospitals for medical care by any means is known as the referred to hospital rate (RTHR).14 Prior research on PPR has produced a wide range of values depending on the nature of the event. For example, an annual, large outdoor music festival in Austria recorded a median PPR of 12.01 per 1,000 attendees.15 In contrast, the 2019 Rugby World Cup in Japan reported a considerably lower rate with a PPR of 2.63 per 10,000.16 The New York State Fair demonstrated an annual PPR of 4.8 per 10,000 attendees.17 Another study exploring various event types found PPRs per 10,000 to be 4.85 at baseball games, 6.75 at football games, and 30 per 10,000 at rock concerts.18 At the South Africa FIFA World Cup, the PPR was 6.6 per 100,000.19 Heat is one important environmental factor affecting PPR and TTHR, leading to various heat-related illnesses; it is on the rise worldwide.20-21 This is most accurately captured by the heat index, which is a calculated value of perceived heat exposure, combining air temperature and relative humidity. The heat index can help better stratify the risk of heat-related illnesses.22 This ranges from mild heat cramps to more severe, life-threatening conditions such as heat exhaustion and heat stroke.23 Several studies have explored the relationship between PPR and temperature; however, few studies look at PPR in the context of the heat index, which provides a more accurate representation 4

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of heat’s effect on the human body.24-25 Perron et al demonstrated that PPR was tied to the heat index at college football games in the southeastern United States during the fall and winter months.25 This study examined whether the correlation persists during summer months by analyzing the impact of heat on patient presentation rates and its potential to strain onsite medical resources and local healthcare systems. We hypothesized that a positive correlation exists between PPR and heat index at large baseball events in a bounded stadium in the northeastern US but that this increase in patients would remain within the capacity of onsite resources.

this data to calculate the heat index using the US National Oceanic and Administration Weather Prediction Center (College Park, MD). Results are reported with descriptive and quantitative statistics. The correlation between heat index and patient presentation rate was assessed with the Pearson productmoment correlation (PPMC). The PPMC is a statistical tool that we used to control stadium attendance as a contributing factor to the overall number of patients seen; we assessed for a positive correlation between the heat index and the ratio of the number of patients cared for per 100,000 attendees at the game. In addition, we performed chi-squared testing to assess for any statistical difference between sexes and final disposition among the chief complaints and treatments rendered.

METHODS This prospective, observational study examined the cases of attendees seeking medical attention during baseball games in a large northeastern city in the US. These games took place outdoors in a bounded stadium with ticketed seats. The stadium has open-air seating and limited natural shade with much of the seating areas exposed. The region’s climate is characterized as humid subtropical with summer temperatures reaching as high as 100° Fahrenheit (F).26 The stadium in this study can accommodate 47,309 spectators. We collected data during regular season games at the stadium between April–September 2023. Patrons could self-present or be brought by emergency medical technicians (EMT) via mobility assist devices and were met by the paramedic supervisor at the front of the medical office. We excluded patrons who self-presented to the medical office solely asking for over-the-counter items such as bandages, acetaminophen, or non-steroidal anti-inflammatory drugs. We included only individuals with acute medical complaints who were then directed for evaluation by a physician. To prevent bias and capture cases of occult heat illness, exacerbations of chronic illness due to heat, and potential sequelae from heat-related crowd behavior, we included all medical complaints. At these events, the responsibility of the onsite physician was to assess the patient, provide initial stabilization, and determine the need for ambulance transport to a nearby hospital. The onsite physician was an emergency physician with medical command training from the surrounding area. The onsite physician gathered data during home games, using Research Electronic Data Capture (REDCap) tools hosted at the Maimonides Medical Center to record patient information such as age, sex, chief complaint, treatments administered, physician diagnosis, and disposition. Non-physician staffing included one EMS supervisor, two paramedics, five EMTs, and one dedicated transport unit. The EMTs were dispersed throughout the crowd to help facilitate patients in reaching the medical office and then returned to continue crowd surveillance after patient handoff. We obtained the total number of attendees at each game from Baseball-Reference.com. Temperature and humidity data was obtained from Time and Date AS (Stavanger, Norway), with the game start time as the reference point. We then used Volume 27, Supplement: November 2026

RESULTS A total of 81 home baseball games occurred from April– September 2023, with eight games excluded due to incomplete data from lack of documentation. There were 92 patient encounters among the 2,926,363 total attendees. The heat index ranged from 46°F-91°F, with a mean (±SD) of 70.8°F (± 10.42°F). The number of patients per game varied from 0-5, with a mean of 1.92 (±1.13), and stadium attendance ranged from 25,007 to 47,295. The PPR in our study is defined as the number of patient presentations per 100,000 attendees. The PPR across all games was 5.04 ± 2.13, with the highest PPR in July (6.09 ± 1.66) and the lowest in April (3.19 ± 1.13) (Figure 1). The average patient age for those seeking medical care was 39.9 years. We calculated the PPMC to be 0.37 (P < .01), indicating a moderately positive correlation between heat index and PPR. Our linear equation demonstrated that for every 10-degree increase in heat index, there was a 1.46 increase in the number of patients requiring emergency care per 100,000 attendees (Figure 2). The mean TTHR was .37 per 100,000 attendees with a peak in June of .60 and a trough in August of .12. The STHR per 100,000 attendees across all games was 0.3 ± 0.6, and our

Figure 1, Mean patient presentation rate by month. PPR, patient presentation rate.

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Association of Heat Index and Patient Presentation Rate at a Bounded Mass-gathering Event

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Treatments rendered similarly had comparable distributions between sex and final dispositions, and no statistical difference was observed (Table 3). Of all patients who presented, 32 (35%) were referred to the hospital., an average of fewer than one patient per game. Fourteen patients elected to refuse transport by EMS and chose to transport themselves by private vehicle, and 18 (19.2%) who presented for physician evaluation were consequently transported via onsite ambulance. There were zero instances where ambulances from the local 9-1-1 system were needed to transport patients from the event. DISCUSSION In this study we examined the correlation between PPR and the heat index at a mass-gathering baseball event. We found a moderate positive correlation between the heat index and PPR. The PPMC was 0.37 (P < .01) with a linear equation demonstrating that there was a 1.46 increase in the number of patients presenting for emergency care per 100,000 attendees for every 10-degree increase in the heat index. This could help inform future planning efforts, especially as the host city is projected to have a tripling of days above 90°F by the year 2050.27 During the study period, there were no instances of outside resources used to render medical aid at the event. Comparing our event to other mass gatherings is challenging because so many studies depict specific events with unique characteristics. It would be potentially inaccurate to make comparisons to non-sporting events due to different crowd behavior and milieu characteristics. In a study involving spectators at a bounded football game, Perron et al found that for every 10-degree increase in heat index, three more patrons per 10,000 attendees would present for care.25 Our findings were most similar to the 2010 South Africa World Cup, which shared key characteristics with our event. Both stadium events had ticketed entry, offered alcohol for

Figure 2. Correlation between heat index and patient presentation rate by degrees in Fahrenheit. PPR, patient presentation rate.

mean RTHR across all games was .67 ± 0.7 (Table 1). Chief complaints were broken down by category. Among patients seeking medical attention, the most frequent complaint was musculoskeletal, affecting 31 patients (34%). This was followed by lightheadedness in 24 patients (26%) and nine patients (10%) who were intoxicated. There were no cardiac arrests in this cohort. These chief complaints were comparable in frequency between male and female patients, as well as between patients transported to the hospital vs those who returned to the event (Table 2). A total of 108 treatments were documented across all games because some patients received multiple treatments. The most common treatments included 33 ice packs (31%), 21 (19%) administered NSAIDs or acetaminophen, 12 (11%) miscellaneous, and 11 patients (10%) who received oral fluids. Two patients received an electrocardiogram (2%), and five received intravenous fluids (5%).

Table 1. Medical usage rates by month. Mean total patients per 100,000 attendees (PPR)

Mean EMS transports per 100,000 attendees

Month April

1.27 ± 0.46 0.08 ± 0.44 0.36 ± 0.50

0.44 ± 0.50 39,765 ± 7,106

0.85 ± 0.15 60.2 ± 8.44

3.19 ± 1.13

0.88 ± 1.25

May

2.00 ± 0.69 0.10 ± 0.67 0.21 ± 0.69

0.31 ± 0.82 38,694 ± 2,132

0.83 ± 0.04 65.8 ± 10.31 5.16 ± 1.95

0.55 ± 0.94

June

2.20 ± 1.68 0.11 ± 0.53 0.60 ±0.69

0.71 ± 0.59 43,511 ± 3,311

0.93 ± 0.07 73.5 ± 4.50

5.05 ± 1.27

1.32 ± 1.52

July

2.66 ± 1.50 0.66 ± 0.81 0.50 ± 0.54

1.16 ± 0.98 43,612 ± 3,433

0.93 ± 0.07 81.2 ± 4.73

6.09 ± 1.66

1.17 ± 1.29

August

1.75 ± 1.03 0.75 ± 0.70 0.12 ± 0.35

0.87 ± 0.64 41,316 ± 3,130

0.88 ± 0.06 76.7 ± 4.68

4.23 ± 2.45

0.29 ± 0.83

September

1.67 ± 0.81 0.50 ± 0.83 0.16 ± 0.40

0.66 ± 0.81 38,472 ± 3,209

0.82 ± 0.06 70.1 ± 9.62

4.34 ± 2.10

0.44 ± 1.08

Mean ± SD 1.92 ± 1.13 0.30 ± 0.61 0.37 ± 0.56

0.67 ± 0.73 40,824 ± 4,550

0.87 ± 0.09 70.8 ± 10.42 5.04 ± 2.13

0.90 ± 1.39

Mean STHR

Mean TTHR via Mean ambulance RTHR

Stadium attendance

Mean stadium capacity filled

Mean heat index in degrees Fahrenheit

Mean number of patients per game

Medical usage rates by month include mean number of patient presentations per game, transport rate to hospital via ambulance, and referred-to-hospital rate. STHR, self-transport to hospital rate; TTHR, transport to hospital rate; RTHR, referred to hospital rate; PPR, patient presentation rate; EMS, emergency medical services.

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Table 2. Overview of chief complaints. Referred to hospital (n = 39)

Total (N = 92)

Male (n = 54)

Female (n = 38)

Chief complaint

Abdominal pain

0.97

Allergic reaction

0.97

0.94

Chest pain

0.93

Intoxication

0.96

Miscellaneous

0.95

0.5

Musculoskeletal

Shortness of breath

0.5

0.8

Lightheadedness

Significance

sale and free water, and resulted in similar medical needs and PPR (5.04 vs 6.6 per 100,000). However, other well-studied events, such as college football games held in similar settings but with different demographics and environmental traits, revealed significantly higher PPRs.28 This suggests that factors beyond venue characteristics, such as crowd mood and behavior, may influence the PPR at mass gatherings. Of all patients who presented for medical care, an average of .67 per 100,000 attendees were referred to nearby hospitals, which likely did not impact operations at local hospitals. Of the 92 patients who presented, 19.2% were transported via ambulance. In months with relatively low heat indexes such as April and May, a single patient was transported via ambulance in one of every three games. However, in months with higher heat index such as June and July, this increased to an ambulance transport every two games. This increase, however, did not meaningfully stress the ability to provide medical aid using our current onsite staffing model.

Back to event (n = 53)

Significance

Overall, the data suggesst a relatively low and predictable PPR at baseball events with a low RTHR and TTHR. However, when compared to similar studies, there is a much higher TTHR in our setting than in others. Patients with the chief complaint of “lightheadedness” were disproportionately more likely to be transported to the hospital, making up 28% of chief complaints but 38% of all transports. In our study, 19.2% of patients were taken to a hospital by ambulance vs 5.7% in Perron et al and 4.1% in Hardcastle et al.19,25 Perron et al found a significantly higher PPR, while only 5.7% of patrons required ambulance transports. Our study also had a higher average patient age than the other referenced studies. Compared to Hardcastle et al, we recorded a mean patient age that was eight years older. Although patient acuity may explain the difference in TTHR, these events also occurred in different countries. The economic burden of paying for ambulance services, and differences in professional liability, may also account for the difference in TTHR.

Table 3. Overview of treatments rendered to patients who presented for medical care. Referred to hospital (n=45)

Back to event (n=63)

0.99

0.98

0.97

0.9

0.8

0.75

0.95

0.97

0.94

Miscellaneous 12 11 4 7 8 15 ECG, electrocardiogram; NSAID, nonsteroidal anti-inflammatory drug .

Total (N=108)

Male (n=56)

Female (n = 52)

Treatment rendered

Bandage

Diphenhydramine

Albuterol nebulizer

ECG

Ice pack

Intravenous fluids

NSAIDs/Acetaminophen

Oral Fluids Ondansetron

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Significance

Western Journal of Emergency Medicine

Association of Heat Index and Patient Presentation Rate at a Bounded Mass-gathering Event We found the most common medical complaints were musculoskeletal followed by lightheadedness. There were no differences in chief complaints between sexess or in the final disposition of the patient. This aligns with other studies on mass gatherings where the predominant complaints were musculoskeletal. In the study by Hardcastle et al, of their 316 presentations, 98 (31%) were also musculoskeletal or minor trauma. There were 108 documented interventions; some patients received multiple interventions while others received none. The physician treated patients with various interventions, with the most common being ice packs (31%), corresponding to 34% of complaints being musculoskeletal. Pain relievers such as NSAIDs and acetaminophen were also frequently used. Oral fluids were the third most common intervention; this is likely under-reported as many patients brought their own water containers. Interestingly, a limited number of ECGs and IV fluid boluses were administered even though Advanced Life Support was available at all events. This suggests that most patients who presented for medical evaluation did not require advanced prehospital intervention and were likely low-acuity patients. There were zero cases of cardiac arrest during the study period. Removing patients from the heat and providing rest helped most recover. The final disposition of patients was similar for each treatment group.

classified all individuals who presented as patients, regardless of physician evaluation, we only included those who were formally evaluated by a physician. This measurement difference contributed to our higher TTHR. While our study shows more patients needing care with a higher heat index, this cannot be extrapolated below 46° F, which was the study’s lowest recorded temperature. Studies suggest that extremely cold temperatures also increase PPR given its association with cold-related medical conditions.28-29 In addition, wedid not us Wet Bulb Globe Temperature (WBGT), which is another modality for temperature measurement that takes into account factors such as humidity, wind, and sunlight.30-33 While not used before for predicting medical needs at spectator sporting events, WBGT is used in active participation event studies, and future research could explore this further, providing a more comprehensive understanding of variables within the environmental domain. CONCLUSION We found that the heat index was moderately associated with higher patient presentation rates at bounded massgathering baseball events. Although no additional onsite resources were needed, likely due to low baseline presentation rates and moderate weather during the study period, this correlation could help inform event medical planning efforts as the climate continues to evolve.

LIMITATIONS Our study has several limitations. Because it was an observational study with a 10% missingness rate, we could only establish a correlation between heat index and patient presentation rates and not causation. The data abstractors were not blinded to the premise of the study. Additionally, only one baseball season was studied, which limited the climate and patient data to one specific year. Because our analysis was limited to a single season, we could not further isolate games with higher heat indices without significantly reducing the sample size. Due to the modest sample size, there is a potential for variability, raising concerns about the robustness of the findings. While a moderate correlation was observed for PPR, no such relationship was found for TTHR. For instance, despite having a similar heat index to June, August had a much lower TTHR and PPR. We chose not to include patients seeking OTC medication who didn’t request to see a physician in order to isolate physician staffing needs and the effect of heat index on patient presentation for medical usage. However, the definition of what constituted a patient encounter likely varied between physicians and resulted in a more heterogeneous population despite our efforts to define it. Some treatment interventions may have been undercounted, such as giving oral fluids to patients. We did not capture data on the total supply usage, such as OTC medications dispensed without physician evaluation. Capturing total supply usage may also be of interest to event directors. Lastly, our high TTHR (19.2%) may reflect how we defined a patient. Unlike other studies that Western Journal of Emergency Medicine

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Address for Correspondence: Eric Quinn, MD, Maimonides Medical Center, Department, 965 48th Street, Brooklyn, NY 11219. Email: equinn@maimo.org. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. Jennifer Wolin, Daniel Wolf, John Su, Eric Quinn, David Eng, Humaira Ali, David Lobel, and Matt Friedman, reports financial support was provided by Maimonides Medical Center. Jennifer Wolin, Daniel Wolf, John Su, Eric Quinn, David Eng, Humaira Ali, David Lobel, and Matt Friedman reports a relationship with Crowd Rx that includes employment. No other author has professional or financial relationships with any companies that are relevant to this study. There are no other conflicts of interest or sources of funding to declare. Copyright: © 2025 Wolin et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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25. Perron AD, Brady WJ, Custalow CB, et al. Association of heat index and

10. Martin-Gill C, Brady WJ, Barlotta K, et al. Hospital-based healthcare

patient volume at a mass gathering event. Prehosp Emerg Care.

provider (nurse and physician) integration into an emergency medical

2005;9(1):49–52.

services-managed mass-gathering event. Am J Emerg Med.

26. NOAA’s National Weather Service. Climate. 2024. Available at: https://

2007;25(1):15-22.

www.weather.gov/wrh/Climate?wfo=okx. Accessed April 9, 2024.

11. Schwartz B, Nafziger S, Milsten A, et al. Mass gathering medical

27. United States Environmental Protection Agency. New York City

care: Resource document for the National Association of EMS

adapts to deal with projected increase of heat waves. 2024. Available

Physicians Position Statement. Prehosp Emerg Care.

at: https://www.epa.gov/arc-x/new-york-city-adapts-deal-projected-

2015;19(4):559–68.

increase-heat-waves. Accessed January 15, 2025.

12. Locoh-Donou S, Yan G, Berry T, et al. Mass gathering medicine: event

28. Kman NE, Russell GB, Bozeman WP, et al. Derivation of a formula to

factors predicting patient presentation rates. Intern Emerg Med.

predict patient volume based on temperature at college football games.

2016;11(5):745-52.

Prehosp Emerg Care. 2007;11(4):453-7.

13. Arbon P, Bottema M, Zeitz K, et al. Nonlinear modelling for predicting

29. Karami M, Doosti-Irani A, Ardalan A, et al. Public health threats in mass

patient presentation rates for mass gatherings. Prehosp Disaster Med.

gatherings: a systematic review. Disaster Med Public Health Prep.

2018;33(4):362-7.

2019;13(5-6):1035-46.

14. Arbon P, Bridgewater FH, Smith C. Mass gathering medicine: a

30. Goldberg SA, Maggin J, Molloy MS, et al. The Gillette Stadium

predictive model for patient presentation and transport rates. Prehosp

Experience: A Retrospective Review of Mass Gathering Events From

Disaster Med. 2001;16(3):150-8.

2010 to 2015. Disaster Med Public Health Prep. 2018;12(6):752-8.

15. Maleczek M, Rubi S, Fohringer C, et al. Medical care at a mass

31. Cheuvront SN, Kenefick RW, Blazy PT, et al. Change of seasons:

gathering music festival : Retrospective study over 7 years (2011-2017).

Boston Marathon Wet Bulb Globe Temperature Index in October.

Wien Klin Wochenschr. 2022;134(7-8):324-31.

Wilderness Environ Med. 2023;34(4):509–12.

16. Tajima T, Takazawa Y, Yamada M, et al. Spectator medicine at an

32. Cheuvront SN, Caruso EM, Heavens KR, et al. Effect of WBGT index

international mega sports event: Rugby World Cup 2019 in Japan.

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17. Grant WD, Nacca NE, Prince LA, Scott JM. Mass-gathering medical

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multi-day mass gathering. Prehosp Disaster Med. 2010;25(2):183-7.

2001;31(10):743-62.

Volume 27, Supplement: November 2026

Western Journal of Emergency Medicine

Original Research

Influence of Daily Meteorological Changes on Stroke Incidence Across the United States Randall L. Ung, MD, PhD Jeffrey S. Lubin, MD, MPH

Penn State Milton S. Hershey Medical Center, Department of Emergency Medicine, Hershey, Pennsylvania

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted November 4, 2024; Revision received March 18, 2025; Accepted March 22, 2025 Electronically published July 11, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.39685

Introduction: Various variables of weather are hypothesized to exert a small but measurable, significant influence on the development of cerebral infarctions (strokes). Improved characterization of this relationship would enhance understanding of the impact of climate change on healthcare demand. However, current data are conflicting regarding the exact nature of the direction and magnitude of the relationship between weather variables and stroke incidence. Methods: We conducted a retrospective analysis using patient data from 2019 across the contiguous United States obtained from the TriNetX global research data network and weather data from the National Oceanic and Atmospheric Administration database. Data from hospitalized patients who had a diagnosis of cerebral infarction, as defined from International Classification of Diseases, 10th Rev, diagnosis codes, were used for analysis. Negative binomial regression calculated the incidence rate ratio (IRR) between stroke and various weather variables: temperature (°C), change in temperature, pressure, change in pressure, and precipitation. Results: Our study included 92,422 patients across 92 healthcare systems. Regression analysis revealed a small but statistically significant association between stroke and change in temperature (IRR 1.0047, confidence interval 1.0012 - 1.0083, P = .010). The remaining variables in our model did not have a statistically significant effect on incidence of stroke. Conclusion: The data suggest that one aspect of weather, specifically day-to-day increases of ambient temperature, has a measurable small magnitude but statistically significant impact on local stroke patterns. [West J Emerg Med. 2026;27(6.1)10–15.]

INTRODUCTION Cerebral infarctions (strokes) are a leading cause of death and disability within the United States (US) and globally,1 and the incidence of strokes has been rising and is expected to continue to rise.2 The occurrence of stroke has been associated with several risk factors, including hypertension, smoking, and diabetes.3-5 The effect of weather on the incidence of stroke is less clear however.6 Geographic trends, such as increased rates of strokes in the southeast region of the US (often referred to as the “stroke belt”), suggest a possible link with weather.7,8 Previous studies have suggested that precipitation, temperature, and pressure effect changes in the incidence of strokes, yet their conclusions are conflicting.9-12

Western Journal of Emergency Medicine

The exact role of these weather variables in the development of stroke, therefore, is controversial. Evolving patterns in weather with climate change are inevitable, and these changes may influence the occurrence of stroke.13 Many areas of the US have experienced dramatic changes in temperature averages and precipitation in recent years; thus, a more comprehensive understanding of the relationship between weather and stroke could be an invaluable tool moving forward. This may aid in preparation and resource allocation for regions and periods at risk for increased cases of stroke. In this study, we incorporated various meteorological variables into a single statistical model to delineate how these factors may influence the incidence of stroke across the contiguous US. 10

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Influence of Daily Meteorological Changes on Stroke

Ung et al. Materials and Methods In this retrospective study we used criteria as outlined in Worster and Bledsoe to optimize the quality of our investigation.14 Specifically, we were trained on use of the databases to identify criteria for inclusion and exclusion, define variables used, define the database used, describe how datapoints were sampled/obtained, and outline management of missing data.

Population Health Research Capsule What do we already know about this issue? Weather variables are hypothesized to exert a small but measurable significant influence on the development of cerebral infarctions (strokes). What was the research question? At a national scale, how do weather variables influence the incidence of strokes within the United States?

Data Collection We collected the data used in this study from the TriNetX Diamond Network, which provided access to electronic health records from approximately 212 million patients from 92 healthcare organizations. The retrospective study was reviewed and accepted by Penn State University’s Institutional Review Board (STUDY00022926 approved June 28, 2023) and determined to be exempt from informed consent. Raw patient and encounter data was extracted from the TriNetX database for analysis on custom scripts in Python (Python Software Foundation, Wilmington, DE) and R (R Foundation for Statistical Computing, Vienna, Austria). (We did not use analytical tools within TriNetX). The study included hospitalized patients ≥ 18 years of age diagnosed with cerebral infarction (as defined using International Classification of Diseases, 10th Rev. code I63). Only the first stroke diagnosis per hospital admission was counted, and admissions within seven days were treated as the same encounter to avoid multiple counts. Cerebral infarction did not need to be the primary diagnosis. Data included only patients within the contiguous US. We excluded regions lacking weather data for specific days or entirely and regions without patient data. We used the data from the National Oceanic and Atmospheric Administration through Google Cloud’s BigQuery to obtain weather variables from weather stations across the contiguous US in 2019. US Census data from BigQuery were used to match the weather station location to the appropriate three-digit ZIP code. In three-digit ZIP code regions with multiple weather station data, we averaged data across all the stations within each region. Of note, in less populous areas of the US (particularly in the West), no ZIP code is defined, and these regions were excluded from analysis. Additionally, some three-digit ZIP code regions lacked weather data for particular days or altogether and were excluded from our analysis. Likewise, regions that lacked patient data from TriNetX were not included in the data. We created custom SQL scripts to obtain and organize weather data for the study. Based on previous studies, we selected temperature, pressure, and amount of precipitation to use for our model. Additionally, the change in both temperature and pressure was calculated as the difference in the current weather value to the average of the previous seven days. We calculated the variance inflation factor to ensure these variables did not have Volume 27, Supplement: November 2026

What was the major finding of the study? Increase in temperature is associated with increase in stroke incidence: IRR 1.0047, CI 1.0012 - 1.0083, P = .01. How does this improve population health? While these findings expand our understanding of weather and stroke relationship, they would not support varying emergency staffing given the small effect size.

significant multicollinearity, maintaining a value < 3. We filtered and merged patient and weather data using custom Python v3.11.5 scripts. Statistical Analysis We used a negative binomial regression mixed-effects model to understand how weather variables affected the incidence of strokes per three-digit ZIP code. A mixed-effects model was used to control for the repeated measures in each three-digit ZIP code region. The incidence rate ratio (IRR) is reported for each weather variable. We scaled data before regression analysis, and regression coefficients were “unscaled” to calculate the incidence rate ratio (IRR) in relatable units. We implemented the Wald method for the calculation of 95% confidence intervals (CI). Statistical analysis was implemented using a combination of custom Python v3.11.5 and R v4.3.1 scripts. RESULTS Our study included 92,422 patients across 349 three-digit ZIP code regions within the US during 2019. After matching with available weather data, 85,355 occurrences of strokes were included in our analysis. Across all three-digit ZIP codes, the average daily incidence of stroke in each region was 0.69 (SD 0.95). Characteristics of the patient population are 11

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Influence of Daily Meteorological Changes on Stroke Incidence outlined in Table 1. Summary statistics for ZIP code regions are outlined in Table 2. Negative binomial mixed-effects regression revealed notable variability in the relationship between weather variables and stroke among the different regions included in our dataset (Figure). The fixed effects from our regression analysis showed that among the weather variables we studied, only the change in temperature had a significant association with the incidence of stroke (Table 3). Specifically, our study showed that an increase in temperature (IRR 1.0047, CI 1.0012-1.0083, P = .01) was associated with a positive change in the incidence of stroke. The remaining variables did not have a significant impact on stroke incidence: temperature (IRR 1.0001, CI 0.9985-1.0017, P = .91), pressure (IRR 0.9999, CI 0.9961-1.0037, P = .94), change in pressure (IRR 1.0021, CI 0.9983-1.0059, P = .28), precipitation (IRR 0.9996, CI 0.9980-1.0012, P = .64).

Table 2. Summary of ZIP code region statistics in a study of the association of weather on the incidence of stroke in the United States. Number of ZIP code regions (N) 349

68 [59-77]

Male

45,854 [49.61 %]

Unknown

4 [< 0.01 %]

Race (n) Black

7,080 [7.66 %]

Asian

262 [0.28 %]

White

20,372 [22.04 %]

Unknown 64,708 [70.01 %] *The total number of patients corresponds to the incidence of strokes across hospital systems within the TriNetX database during 2019. IQR, interquartile range.

Western Journal of Emergency Medicine

1016.4 ± 1.4 3.1 ± 1.2

several cardiovascular diseases are similarly influenced by daily temperature changes, specifically that the daily range in temperature increases hospitalizations related to cardiovascular disease.15 This hypothesis extends to stroke.6,16 A recent multicenter study across 567 cities in 27 countries showed that deaths (vs incidence in our study) related to strokes and other cardiovascular diseases were increased in days with extreme temperatures.17 However, other studies have come to conflicting conclusions, complicating our understanding of this relationship. No consensus exists regarding the exact nature between meteorological variables and strokes. Our data are consistent with data that suggest increased temperature and warmer seasons increase the incidence of stroke.10,16,18,19 These studies span multiple geographic locations with specific studies located in Scotland,10 Qatar,18 and the US,19 suggesting that this relationship may be generalizable across the globe and is not restricted to one specific geographic area or climate. On a cellular basis, multiple physiological mechanisms may drive this idea. One explanation is increased endothelial dysfunction with increased temperature.20 One study used flow-mediated dilation of the brachial artery as a proxy for endothelial function and found that warmer temperatures dampened the ability of the brachial artery to dilate in the setting of ischemia. Additionally, dehydration has been proposed as a possible mechanism for increased incidence of stroke considering its increased likelihood in the setting of warmer weather, but one study in Qatar failed to show this as a contributing factor.18 Blood pressure also changes with temperature,21 but this is unlikely to explain our finding considering that blood pressure decreases with warmer temperatures. A decrease in blood pressure would not likely be associated with an increased incidence of strokes. However, many studies also show that stroke incidence increases with decreases in temperature as during winter months.9,11,12 Further, other studies suggest that both cold and hot weather can increase the occurrence of strokes with extreme temperatures in either direction being the driving force.16,17 Considering that extreme warm temperatures are likely associated with large changes in temperatures, this is not

Sex (n [%]) 46,465 [50.27 %]

13.2 ± 5.6

Pressure (hPa, mean ± SD)

Mean incidence of stroke (mean ± SD) 0.69 ± 0.95 * Incidence represents the mean number of strokes across all three-digit ZIP codes for hospital systems that are included in the database. hPa, hectopascal; mm, millimeters.

Table 1. Summary of patient statistics in a study of the association of weather on the incidence of stroke in the United States. Total patients (N) 92,422

Female

Temperature (°C, mean ± SD) Mean precipitation (mm, mean ± SD)

DISCUSSION This study suggests that one variable characterizing daily weather patterns has a small but statistically significant impact on the incidence of strokes across the contiguous US. Specifically, increases in daily temperature from the prior seven-day average are associated with significant small but measurable increases in the incidence of strokes. Results suggest that for every 1°C increase of temperature, the rate of stroke is increased by 1.0047 times, or 0.47%. This translates to a 4.8% increase in stroke incidence for a 10°C increase in temperature. The magnitudes of daily temperature, pressure, changes in pressure, and precipitation were not associated with statistically significant changes in stroke incidence. Our findings add to the current and somewhat conflicting literature regarding the effect of weather on stroke. Weather has been hypothesized to influence a variety of cardiovascular diseases including strokes. A recent study in Japan found that

Age (median [IQR])

Ung et al.

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Influence of Daily Meteorological Changes on Stroke

Ung et al.

Figure. Incidence rate ratios for ZIP code regions as defined by random effects of negative binomial mixed-effects regression. Maps illustrate the relationship between weather variables and stroke. Each map depicts the IRR for each variable used in our regression model as a colored circle. Circles filled green depict a positive relationship between the variable and stroke incidence while magenta represents a negative association. Gray-filled circles have a weaker or zero association. The geography of ZIP code regions included in our analysis are outlined in gray. IRR, incidence rate ratio.

necessarily conflicting with our results. Lastly, the effect of temperature may depend on the type of stroke with one study showing that increases in temperature increased incidence of ischemic stroke but decreased the incidence of hemorrhagic stroke.19 Previous investigations have also shown that atmospheric pressure is associated with the development of strokes. However, our study failed to show an influence of atmospheric pressure and strokes. One study in the United States also failed to show a significant relationship between stroke and atmospheric pressure.22 Interestingly, this same study did show that decreases in atmospheric pressure were associated with increases in acute myocardial infarction suggesting weather may differentially affect different cardiovascular diseases. The notion that atmospheric pressure may not incur changes in stroke risk may explain the heterogeneity within the literature, with some studies showing a positive relationship23,24 and others showing the opposite.10,18 Volume 27, Supplement: November 2026

Precipitation has been the focus of fewer studies compared to temperature and pressure, and studies have also had conflicting conclusions on its relationship with stroke.25,26 In our study, precipitation did not statistically affect stroke incidence. Although precipitation does not appear to influence the incidence of strokes, one study found increased precipitation was associated with improved outcomes in patients admitted for stroke.11 Unfortunately, the culmination of multiple studies assessing weather and stroke has not provided a clear consensus on the exact nature of their relationship. Varying methodologies may explain the discrepancies among the many studies, including ours. For one, several limitations exist in prior studies diminishing the generalizability of their conclusions. Varying geographic regions and different timescales used between studies may explain some of the conflicting conclusions. For instance, results from studies within a single city or small geographic region may have a strong effect on local stroke incidence but are poorly 13

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Influence of Daily Meteorological Changes on Stroke Incidence

CONCLUSION Our study suggests that increases in temperature have a positive association with stroke incidence. Our analysis benefits from multiple factors including a more precise timescale of days, more refined geographic regions at the three-digit ZIP code level, a diverse set of climate regions, and evaluation of multiple weather variables in a single model. While our study demonstrates a statistically significant association between temperature changes and stroke incidence, the effect size is small. Given that ischemic stroke patients constitute a small minority of patients seen daily in an emergency department, these findings would not support varying staffing based on temperature changes alone. The impact of temperature changes on stroke incidence, although measurable, is limited in its practical implications for emergency department operations and population health.

Table 3. Summary of mixed-effects negative binomial regression in a study of the association of weather on the incidence of stroke in the United States. Variable

IRR

Temperature (°C)

1.0001

0.9984-1.0017

.91

Change in temperature (°C)

1.0047

1.0012-1.0083

.01*

Pressure (hPa)

0.9999

0.9961-1.0037

.94

Change in pressure (hPa)

1.0021

0.9983-1.0059

.28

Precipitation (mm) 0.9988 0.9980-1.0012 .64 IRR, incidence rate ratio; CI, confidence interval; °C, Celsius; hPa, hectopascal; mm, millimeters.

generalizable. The regional variability observed in our study, with some areas showing an increase in stroke incidence and others showing a decrease (Figure), can be attributed to several factors. Geographic and climatic differences, population characteristics, and local behaviors may all play a role in modulating the impact of temperature changes on stroke incidence. For example, regions with more extreme temperature fluctuations may experience different effects compared to regions with more stable climates. Additionally, studies that average weather variables over large timescales, such as seasons, may mask important weather dynamics that happen on the timescale of days. Further, many studies focus only on a single meteorological variable without considering complex weather dynamics. Therefore, incorporating these factors into a single framework may better delineate the relationship between stroke and weather in a more generalizable fashion. This is one of the main advantages that our study addresses. Our data cover a wide region, including diverse geographical and climate regions throughout the contiguous US. Additionally, the precision of our analysis is on the scale of days and incorporates multiple meteorological variables. Many previous studies did not have these advantage.10,11 However, some studies go even further showing that temperature may influence strokes at the timescale of hours,19 and this may provide a clearer picture of how weather drives the onset of stroke.

Address for Correspondence: Randall L. Ung, MD, PhD, Atrium Health, Department of Emergency Medicine, 8800 N. Tyron St, Charlotte, NC 28262. Email: rung@wakehealth.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2025 Ung et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES 1. Feigin VL, Brainin M, Norrving B, et al. World Stroke Organization (WSO): Global Stroke Fact Sheet 2022 [published correction appears in Int J Stroke. Int J Stroke. 2022;17(1):18-29. 2. Tsao CW, Aday AW, Almarzooq ZI, et al. Heart Disease and Stroke Statistics-2022 Update: a report from the American Heart Association. Circulation. 2022;145(8):e153-639. 3. O’Donnell MJ, Chin SL, Rangarajan S, et al. Global and regional

LIMITATIONS Our study is not without limitations. One of its limitations is that isolating the effects of meteorological variables is inherently difficult. Randomized control trials are not possible, and changes in the weather will undoubtedly cause changes in other health-related variables such as increased activity on more pleasant days leading to possible confounders. Our study is also limited to data from a single year. For greater generalizability, additional data spanning multiple years would be beneficial. This may further describe how climate change specifically has influenced this relationship between stroke and weather. Additional data on patient demographics may also highlight important socioeconomic factors. Western Journal of Emergency Medicine

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effects of potentially modifiable risk factors associated with acute stroke in 32 countries (INTERSTROKE): a case-control study. Lancet. 2016;388(10046):761-75. 4. George MG. Risk factors for ischemic stroke in younger adults: a focused update. Stroke. 2020;51(3):729-35. 5. Hankey GJ. Population impact of potentially modifiable risk factors for stroke. Stroke. 2020;51(3):719-28. 6. McArthur K, Dawson J, Walters M. What is it with the weather and stroke? Expert Rev Neurother. 2010;10(2):243-9. 7. Rich DQ, Gaziano JM, Kurth T. Geographic patterns in overall and specific cardiovascular disease incidence in apparently healthy men in the United States. Stroke. 2007;38(8):2221-7.

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Ung et al. 8. Glymour MM, Kosheleva A, Boden-Albala B. Birth and adult

extreme temperatures and cardiovascular cause-specific mortality:

residence in the Stroke Belt independently predict stroke mortality.

results from 27 countries. Circulation. 2023;147(1):35-46.

Neurology. 2009;73(22):1858-65.

18. Salam A, Kamran S, Bibi R, et al. Meteorological factors and

9. Anderson N, Feigin V, Bennett D, et al. Diurnal, weekly, and seasonal

seasonal stroke rates: a four-year comprehensive study. J Stroke

variations in stroke occurrence in a population-based study in

Cerebrovasc Dis. 2019;28(8):2324-31.

Auckland, New Zealand. N Z Med J. 2004;117(1202):U1078.

19. Rowland ST, Chillrud LG, Boehme AK, et al. Can weather help

10. Dawson J, Weir C, Wright F, et al. Associations between

explain “why now?”: the potential role of hourly temperature as a

meteorological variables and acute stroke hospital admissions in the

stroke trigger. Environ Res. 2022;207:112229

west of Scotland. Acta Neurol Scand. 2008;117(2):85-9.

20. Nawrot TS, Staessen JA, Fagard RH, et al. Endothelial function and

11. Chu SY, Cox M, Fonarow GC, et al. Temperature and precipitation

outdoor temperature. Eur J Epidemiol. 2005;20:407–10.

associate with ischemic stroke outcomes in the United States. J Am

21. Modesti PA, Morabito M, Bertolozzi I, et al. Weather-related

Heart Assoc. 2018;7(22):e010020.

changes in 24-hour blood pressure profile: effects of age and

12. Matsumaru N, Okada H, Suzuki K, et al. Weather fluctuations may

implications for hypertension management. Hypertension.

have an impact on stroke occurrence in a society: a population-based

2006;47(2):155-61.

cohort study. Cerebrovasc Dis Extra. 2020;10(1):1-10.

22. Houck PD, Lethen JE, Riggs MW, eta l. Relation of atmospheric

13. Khatana SAM, Eberly LA, Nathan AS, et al. Projected change in the

pressure changes and the occurrences of acute myocardial infarction

burden of excess cardiovascular deaths associated with extreme

and stroke. Am J Cardiol. 2005;96(1):45-51.

heat by midcentury (2036-2065) in the contiguous United States.

23. Gunes H, Kandis H, Saritas A, et al. The relationship between

Circulation. 2023;148(20):1559-69.

ischemic stroke and weather conditions in Duzce, Turkey. World J

14. Worster A, Bledsoe RD, Cleve P, et al. Reassessing the methods of

Emerg Med. 2015;6(3):207-11.

medical record review studies in emergency medicine research. Ann

24. Qi X, Wang Z, Xia X, et al. Potential impacts of meteorological

Emerg Med. 2005;45(4):448-51.

variables on acute ischemic stroke onset. Risk Manag Healthc Policy.

15. Yoneyama K, Nakai M, Higuma T, et al. Weather temperature and the

2020;13:615-21.

incidence of hospitalization for cardiovascular diseases in an aging

25. Matsumoto M, Ishikawa S, Kajii E. Cumulative effects of weather on

society. Sci Rep. 2021;11(1):10863.

stroke incidence: a multi-community cohort study in Japan. J

16. Lian H, Ruan Y, Liang R, et al. Short-term effect of ambient

Epidemiol. 2010;20(2):136-42.

temperature and the risk of stroke: a systematic review and meta-

26. Tang C, Liu X, He Y, et al. Association between extreme precipitation

analysis. Int J Environ Res Public Health. 2015;12(8):9068-88.

and ischemic stroke in Hefei, China: hospitalization risk and disease

17. Alahmad B, Khraishah H, Royé D, et al. Associations between

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burden. Sci Total Environ. 2020;732:139272.

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Expert Commentary

Emergency Medicine at the Frontline of Climate Change: The Role of Geographic Information Systems Tushara Surapaneni, MD* Anna Patrikakou, MA, MSC† Antigoni Faka, PhD‡ Liz Grant, PhD§ Andrew Ulrich, MD* Dimitrios Tsiftsis, MD|| Eleanor Reid MD, PhD*

*Yale School of Medicine, Department of Emergency Medicine, New Haven, Connecticut † 2nd Regional Health Authority of Piraeus and the Aegean islands – Piraeus, Greece ‡ Harokopio University of Athens, Department of Geography, Athens, Greece § University of Edinburgh, Global Health Academy, Usher Institute, Edinburgh, United Kingdom || Nikaia General Hospital, Department of Emergency Medicine, Nikaia, Greece

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted March 17, 2025; Revision received April 30, 2025; Accepted April 27, 2025 Electronically published July 18, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.47035

[West J Emerg Med. 2026;27(6.1)16–19.]

INTRODUCTION The practice of emergency medicine (EM) is becoming inseparable from public health threats like climate change. As leaders in mass casualty management and prehospital care,1 emergency clinicians serve at the frontlines of disaster preparedness and response. With the rising incidence of natural disasters causing humanitarian emergencies,2 it is imperative for population-based research to incorporate a spatial lens—one that extends beyond hospital departments and fosters collaboration across scientific disciplines. While several medical journals have published articles about the implications of climate change on human health,3-9 these discussions need to be accompanied by actionable strategies to strengthen disaster preparedness. Just as meteorologists study weather patterns, EM researchers are uniquely positioned to leverage spatial technology to anticipate disaster-related surges in patient volume and pathology. In recognition that some countries are dually burdened by high climate vulnerability and underdeveloped emergency care systems, we propose geographic information systems (GIS) as an underutilized tool in EM research to strengthen climate resilience. To emphasize the potential of GIS as a powerful supplement to EM research and disaster preparedness planning, particularly in countries with high climate vulnerability, we introduce GIS followed by a case study of Greece to demonstrate its potential.

quantities of geographic data, including elevation, land cover, meteorological observations, and population demographics. Geographic information systems can readily integrate and analyze multiple types of data to create visually informative maps of hazard risk (Figure 1). Several GIS platforms are available, some of which are open access. While they may differ in package offerings, every GIS is a fundamentally iterative system, an essential feature for preparedness systems in the face of a climate crisis with no end date. GIS applications for disaster preparedness As the frequency of natural disasters continues to rise annually, emergency care systems globally can leverage GIS to

What are geographic information systems? Key components of disaster management include planning evacuation routes, identifying shelters and medical facilities, mapping disaster risk, developing early warning systems, and monitoring hazard progression.10 Creating a climate-resilient disaster preparedness system inherently requires large Western Journal of Emergency Medicine

Figure 1. Various data layers can be combined in geographic information systems software to visualize climate hazard risk of a study area.

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EM at the Frontline of Climate Change

Surapaneni et al. become proactive, rather than reactive, to the next climate disaster. Analysis is possible at a range of granularity, from census tracts to entire continents, making GIS highly scalable for study areas. The creation of a GIS-based prediction system is accomplished in three phases: data preparation; spatial modeling; and cross-validation.11 Historical data from prior natural disasters can be used to test and cross-validate prediction models, enhancing their accuracy. There is a robust body of literature describing methods for prediction modeling of various climate hazards including wildfires,12-13 landslides,14 and floods.15-16 In the aftermath of a severe weather event, remote-sensing and satellite imagery can be integrated with on-the-ground needs assessments to improve real-time situational awareness. A centralized GIS database also supports continuous data collection from field surveys, minimizing “false perceptions” of ground conditions that often arise during crises.17 Impact of climate change on emergency care systems Severe weather events such as heatwaves, wildfires, hurricanes, floods, earthquakes, landslides, drought, and tsunamis affect high-, middle- and low-income countries alike, but their impact is felt inequitably. The World Health Organization states: In the short- to medium-term, the health impacts of climate change will be determined mainly by the vulnerability of populations, their resilience to the current rate of climate change and the extent and pace of adaptation.18

Figure 2. Greece’s geography increases its risk of severe weather events.

Accordingly, it is important to examine cases where natural disasters disproportionately threaten health systems to better understand regional differences in “vulnerability.” Countries with fragile emergency care systems are more susceptible to the long-term impacts of severe weather events due to a lack of resources to appropriately prepare and respond. Many also face geographical constraints to service delivery in remote communities, such as underdeveloped road networks, challenging terrain, and island chains. Even during non-disaster times, the availability of specialized equipment and EM-trained staff varies across countries. Greece (Figure 2) provides an example of a country coping with challenging geography, an underdeveloped emergency care system, and high frequency of severe weather events.

landslides and infrastructure damage. The Mediterranean climate contributes to severe wildfires every summer, while Greece’s extensive coastline and islands are exposed to flooding from cyclones and hurricanes. Climate change intensifies these threats, as increasing temperatures and rising sea levels lead to more frequent heatwaves and storms, coastal erosion, ecosystems disturbance and, consequently, significant public health threats. From 1980 to 2020, Greece experienced an average of 26 floods per year. Between 2014-2018, floods and earthquakes were the most frequent natural disasters, but wildfires and heatwaves became increasingly prevalent from 2018 to 2023.20-21 In a list of 35 European nations, Greece ranked sixth highest in the number of heat-related deaths during the summer of 2022.22 Climate predictions for Greece have estimated that the number of days with extreme fire risk will increase by 10-15 days annually, with upwards of 15-20 heatwaves per year by 2050, along with increased flash flood events.23-25 As extreme weather events rise, so will the number of climate-related health conditions, injuries, and deaths. The growing health risks associated with climate change represent an imminent threat to the health of entire populations, and the emergency department (ED) plays a critical role as the first

Case study: Greece’s climate vulnerabilities and emergency care challenges We present Greece as a case study of a country with high vulnerability to climate stressors given its geography, extreme heat, and surrounding seismic activity. Its mountainous terrain creates localized weather conditions, leading to flash floods in some regions and droughts in others. Earthquakes, which have occurred as recently as February 2025,19 are common due to Greece’s location on tectonic plate boundaries and can lead to Volume 27, Supplement: November 2026

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point of contact for people seeking urgent medical care. In Greece, EM is a developing specialty, with a limited number of EM-trained physicians and persistent staffing shortages in public hospitals. The centralized oversight of the Greek Ministry of Health can lead to delayed responses to critical staffing needs, particularly during seasonal influxes of refugees and tourists. On Greece’s islands, baseline challenges of understaffing, a lack of EM-trained attendings, and a fluctuating census of non-permanent residents are further complicated by the hospitals’ remote locations, making them reliant on air ambulances for patient transfers to the mainland.26

Address for Correspondence: Tushara Surapaneni, MD, Yale School of Medicine, Department of Emergency Medicine, 464 Congress Ave #260, New Haven, CT 06519. Email: tushara. surapaneni@yale.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2025 Surapaneni et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

GIS applications for disaster preparedness in Greece In Greece, GIS has the potential to play a vital role in improving climate resilience and minimizing health threats from severe weather events. Greek researchers already use GIS to map fire-prone areas, modeling temperature, humidity, wind speed, and land cover data.27-29 These spatial prediction models enable better resource allocation, evacuation planning, and strategic placement of firebreaks. Remote sensing and satellite data have also been incorporated for real-time monitoring, providing acute data on fire location, size, and direction to aid emergency response efforts.30 To assess flood risk, several studies in Greece have used topographic and rainfall data to design flood protection projects.31-33 The next step is to integrate climate research with sociodemographic and health data to create risk maps of conditions such as heat-related illnesses, pollution-related respiratory diseases, and traumatic injuries after natural disasters. Future research studies can use GIS to do the following: • Predict the health impacts of high temperatures, wildfires, and floods on vulnerable groups of patients; • Guide hospital administration to preemptively request additional staff and resources, enabling timely infrastructure improvements and coordinated response effort; • Inform equitable distribution of resources to underserved or geographically vulnerable communities.

REFERENCES 1. European Union of Medical Specialists. European Training Requirements for the Specialty of Emergency Medicine. UEMS. 2024:636. Available at: http://www.uems.eu/. Accessed February 5, 2025. 2. United Nations Office for the Coordination of Humanitarian Affairs (OCHA). Global Humanitarian Overview 2024. 2023. Available at: https://www.unocha.org/publications/report/world/globalhumanitarian-overview-2024-enarfres. Accessed February 5, 2025. 3. Romanello M, Walawender M, Hsu SC, et al. The 2024 report of the Lancet Countdown on health and climate change: facing recordbreaking threats from delayed action. Lancet. 2024;404(10465):1847-96. 4. Sorensen CJ, Salas RN, Rublee C, et al. Clinical implications of climate change on US emergency medicine: challenges and opportunities. Ann Emerg Med. 2020;76(2):168-78. 5. Ghazali DA, Guericolas M, Thys F, et al. Climate change impacts on disaster and emergency medicine focusing on mitigation disruptive effects: an international perspective. Int J Environ Res Public Health. 2018;15(7):1379. 6. Haines A, Ebi K. The imperative for climate action to protect health. N Engl J Med. 2019;380(3):263-73. 7. Andersen ZJ, Vicedo-Cabrera AM, Hoffmann B, et al. Climate change and respiratory disease: clinical guidance for healthcare

CONCLUSION Geography is a key determinant of health, but it is often overlooked in emergency medicine research. Amid the shift-to-shift demands of emergency medicine, it can be difficult to contextualize how environmental changes are affecting the health of communities. We argue that disaster preparedness systems in climate-vulnerable countries could be more effective if specialists in medicine, climate science, geography, and epidemiology collaborated on data-driven solutions. Emergency medicine researchers can partner with geospatial experts within their hospitals or local universities to harness the potential of geographic information systems. By forecasting “when” and “where” climate-related health conditions will escalate, GIS can empower health systems to prepare for “who” arrives at the emergency department. Western Journal of Emergency Medicine

professionals. Breathe (Sheff). 2023;19(2):220222. 8. Bell ML, Gasparrini A, Benjamin GC. Climate change, extreme heat, and health. N Engl J Med. 2024;390(19):1793-801. 9. Ebi KL, Vanos J, Baldwin JW, et al. Extreme weather and climate change: population health and health system implications. Annu Rev Public Health. 2021;42:293-315. 10. Pitandoyo AB, Nugroho LE, Hantono BS. GIS-based disaster preparedness and mitigation applications: a systematic review on methods, features, and visualization. 2024 2nd International Conference on Technology Innovation and Its Applications (ICTIIA). 2024:1-6. 11. Chung CJF, Fabbri AG, Jang DH, et al. Risk assessment using spatial prediction model for natural disaster preparedness. In: van Oosterom P, Zlatanova S, Fendel EM, eds. Geo-Information for

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Surapaneni et al. Disaster Management. Princeton, NJ: Springer Publishing; 2005:636.

23. Georgakopoulos T. The consequences of climate change in

12. Arango E, Nogal M, Sousa HS, et al. GIS-based methodology for

Greece. Dianeosis. 2021. Available at: https://www.dianeosis.org/

prioritization of preparedness interventions on road transport under

en/2021/12/the-consequences-of-climate-change-in-greece/.

wildfire events. Int J Disaster Risk Reduct. 2023;94:103674.

Accessed January 21, 2025.

13. Gonçalves A, Oliveira S, Zêzere JL. Assessing wildfire exposure and

24. Giannakopoulos C, Kostopoulou E, Varotsos KV, et al. An integrated

social vulnerability at the local scale using a GIS-based

assessment of climate change impacts for Greece in the near future.

approach. MethodsX. 2024;12:102650.

Reg Environ Change. 2011;11(4):829-843.

14. Nsengiyumva JB, Luo G, Nahayo L, et al. Landslide susceptibility

25. Kostopoulou E, Giannakopoulos C, Mirasgedis S. (2024). Aspects of

assessment using spatial multi-criteria evaluation model in

climate change in Greece. In: Darques R, Sidiropoulos G, Kalabokidis

Rwanda. Int J Environ Res Public Health. 2018;15(2):243.

K, eds. The Geography of Greece (p. 447-64). World Regional

15. Wang Z, Chen X, Qi Z, Cui C. Flood sensitivity assessment of super

Geography Book Series. Princeton, NJ: Springer Publishing.

cities. Sci Rep. 2023;13(1):5582.

26. Tsiftsis D, Ulrich A, Notas G, Patrikakou A, Reid E. The state of

16. Rawat PK, Belho K, Rawat MS. Geo-environmental GIS modeling to

emergency medicine in Greece: at critical momentum. Int J Emerg

predict flood hazard in heavy rainfall eastern Himalaya region: a

Med. 2024;17(1):46.

precautionary measure towards disaster risk reduction. Environ Monit

27. Adaktylou N, Stratoulias D, Landenberger R. Wildfire risk assessment

Assess. 2025;197(2):220.

based on geospatial open data: application on Chios, Greece. ISPRS

17. Giardino M, Perotti L, Lanfranco M, et al. GIS and geomatics for

Int J Geo-Inf. 2020;9(9):516.

disaster management and emergency relief: a proactive response to

28. Maniatis Y, Doganis A, Chatzigeorgiadis M. Fire risk probability

natural hazards. Appl Geomat. 2012;4(1):33-46.

mapping using machine learning tools and multi-criteria decision

18. World Health Organization. Climate change and health. 2023.

analysis in the GIS environment: a case study in the National Park

Available at: https://www.who.int/news-room/fact-sheets/detail/

Forest Dadia-Lefkimi-Soufli, Greece. Appl Sci (Basel).

climate-change-and-health. Accessed January 11, 2025.

2022;12(6):2938.

19. Associated Press. Scientists say several thousand earthquakes

29. Sakellariou S, Tampekis S, Samara F, et al. Determination of fire risk

detected near Greece’s island of Santorini. AP News. 2025. Available at:

to assist fire management for insular areas: the case of a small

https://apnews.com/article/greece-santorini-earthquakes-evacuation-f34

Greek island. J For Res. 2019;30(2):589-601.

77a7000f547d2c6b3b5d797612a70. Accessed February 28, 2025.

30. Thangavel K, Spiller D, Sabatini R, et al. Near real-time wildfire

20. CRED. 2023: Disasters in Numbers. Brussels: CRED, 2024. Availble

management using distributed satellite system. IEEE Geosci Remote

at: https://files.emdat.be/reports/2023_EMDAT_report.pdf. Accessed

Sens Lett. 2023;20:5500705.

March 5, 2025.

31. Efraimidou E, Spiliotis M. A GIS-based flood risk assessment using

21. Neofotistou V. Natural disasters’ impact in Greece over the last 10

the decision-making trial and evaluation laboratory approach at a

years as revealed from EM-DAT. International Conference on

regional scale. Environ Process. 2024;11(1):9.

Humanitarian Crisis Management (KRISIS 2023). Thessaloniki,

32. Karymbalis E, Andreou M, Batzakis DV, et al. Integration of GIS-

Greece. 2025. Available at: https://www.ihu.gr/ucips/wp-content/

based multicriteria decision analysis and analytic hierarchy process

uploads/sites/4/2023/12/KRISIS_2023_paper_18_Neofotistou.pdf.

for flood-hazard assessment in the Megalo Rema River catchment

22. Statista. Number of heat-related deaths in selected European

(East Attica, Greece). Sustainability. 2021;13(18):10232.

countries during the summer of 2022. Statista. Available at: https://

33. Kourgialas NN, Karatzas GP. A national scale flood hazard mapping

www.statista.com/statistics/1401196/heat-related-deaths-europe-

methodology: the case of Greece – protection and adaptation policy

summer-2022/. Accessed March 11, 2025.

approaches. Sci Total Environ. 2017;601-602:441-52.

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Review

Association of Rising Ambient Temperatures with Increased Violence Worldwide: Systematic Review and Meta-Analysis Vivek Chauhan, MD* Suman Thakur, MD* Sagar Galwankar, MBBS, MPH† Sarah Temple, MD†

*Indira Ghandi Medical College and Hospital, Department of Medicine, Shimla, Himachal Pradesh, India † Florida State University College of Medicine Emergency Medicine Residency Program at Sarasota Memorial Hospital, Department of Emergency Medicine, Florida

Section Editor: Gary Gaddis, MD Submission history: Submitted January 26, 2025; Revision received April 15, 2025; Accepted April 14, 2025 Electronically published September 25, 2025 Full text available through open ccess at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.42055

Introduction: Climate change has significantly impacted human health worldwide, contributing to the rise of emerging infectious diseases, allergies, pollution, natural disasters, non-communicable diseases, and malnutrition. One crucial but often overlooked area where climate change has had a notable effect is upon interpersonal violence. Methods: Following PRISMA guidelines, we searched PubMed and Epistemonikos for studies measuring the effect of temperature on violence. Inclusion criteria encompassed peer-reviewed, English-language articles reporting an association between temperature and violence. Data extraction focused on various forms of violence including homicides, assaults, sexual assaults, suicides, intimate partner violence, riots, and civil wars, and we assessed article quality using Joanna Briggs Institute criteria. Results: We included a total of 37 studies from 11 countries, three subcontinental regions, and two global-level analyses in this review. Of these, 46% originated from the United States. Rising ambient temperatures were significantly associated with increases in homicides (10 studies), assaults (15 studies), sexual assaults (8 studies), firearm violence (5 studies), intimate partner violence (9 studies), and suicides involving violent methods (9 studies). Conversely, no association was found between temperature and non-violent crimes. Civil wars and riots were also linked to temperature increases in all relevant studies. A meta-analysis of eight studies on violence showed that each 1°C increase in ambient temperature results in 1.64% (95% CI 1.23-2.19%) increase in violence (P<.01). Conclusion: This review demonstrates a significant association between rising temperatures and increased worldwide incidents of violence and self-harm. These findings underscore the urgent need for public health strategies and interventions to mitigate the societal and health impacts of climate change-induced temperature increases. [West J Emerg Med. 2026;27(6.1)20–29.]

INTRODUCTION The global rise in temperatures due to climate change is a well-documented phenomenon with widespread effects on the environment, economy, and human health. While attention has been focused on the physical and environmental consequences of climate change, less consideration has been given to its impact on social behavior. A recently published overview of 94 systematic reviews published since 2015 on the impact of

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climate on human health showed that the reviews covered 10 health outcomes with the three most common being infectious diseases, mortality, and respiratory/cardiovascular/neurological diseases.1 One critical issue missing from the summary of these 94 systematic reviews was the link between increased temperatures and violence, both interpersonal and collective. Violence, broadly defined as physical force intended to cause harm, manifests in several forms including homicides,

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Rising Ambient Temperatures and Their Association with Increased Violence

assaults, intimate partner violence (IPV), sexual assaults, suicides, and collective violence such as riots and civil wars. Studies across diverse geographical regions have suggested that warmer temperatures can exacerbate violent behavior, likely due to a combination of physiological and psychological factors. For instance, higher temperatures are thought to increase irritability and aggression, reduce inhibition, and heighten arousal, all of which may contribute to violent acts.2 While the relationship between temperature and violence is becoming increasingly recognized, the mechanisms underlying this connection remain poorly understood. Our goal was to review the existing evidence on the impact of rising temperatures on various forms of violence. Through examining studies from various nations, we sought to provide a comprehensive understanding of this neglected but critical public health issue, highlighting the need for interventions to mitigate violence in a warming world.

Population Health Research Capsule What do we already know about this issue? Research has shown an association between ambient temperatures and interpersonal violence. What was the research question? What is the impact of rising ambient temperature on various types of violence? What was the major finding of the study? The meta-analysis of 8 studies on violence showed that each 1°C increase in ambient temperature results in 1.64% (95% CI 1.23-2.19%) increase in violence (P<.01).

METHODS We performed a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methods3 using the protocol published in the International Prospective Register of Systematic Review (PROSPERO) (CRD42024581202).

How does this improve population health? Proactive preparedness during extreme heat events could help alleviate the burden of violence-related injuries and mental health issues on public health systems and law enforcement.

Search Strategy We searched two open-access databases, PubMed and Epistemonikos, on July 30, 2024 for peer-reviewed articles on violence and temperature. We operationalized different permutations of each keyword for the two databases as follows: Pubmed: ((Temperature) OR (‘heat wave’) OR (‘extreme heat’) OR (‘cold wave’) OR (‘extreme cold’)) AND (“Violence” [Mesh]) Epistemonikos: (title:(Violence) OR abstract:(Violence)) AND (title:(Temperature OR “heat wave” OR “cold spell” OR “extreme heat” OR “extreme cold”) OR abstract:(Temperature OR “heat wave” OR “cold spell” OR “extreme heat” OR “extreme cold”))

violence, civil wars, etc); and outcome data (effect of temperature on violence). Study Quality We used the Joanna Briggs Institute’s critical appraisal checklist for evaluation of the quality of the analytical, cross-sectional studies.4 The tool was applied to all studies that were included in the review. None of the studies were excluded based on the outcome of quality assessment. The tool assessed quality using eight questions. A score of 1 was assigned for the answer “Yes,” and a score of 0 was assigned for the answer “No,” “unclear,” or “not applicable.” The scores were graded as low, moderate or high if the total score was ≤ 3, 4-6, and ≥ 7, respectively. The quality assessment was performed independently by two investigators, and any disagreement was settled by discussion.

Screening and Eligibility We applied a series of inclusion and exclusion criteria. Articles were included if they were 1) written in English, 2) published in a peer-reviewed journal, and 3) studied the association of temperature with violence. We excluded articles if they 1) were not original, 2) did not describe the effect of temperature on violence, or 3) were a systematic review.

RESULTS Literature Search Our initial search resulted in 247 results in PubMed and 22 in Epistemonikos, which were imported into EndNote reference management software (Clarivate, London, United Kingdom). Of these 269 articles, 10 were duplicates, leaving 259 articles for the screening and eligibility stages (Figure 1). Of the 259 articles screened, we excluded 188 that did not meet the

Extraction and Analysis Extraction was performed by two investigators independently, who obtained the following information: study characteristics (first author, year of publication, country, years for which violence-related data was collected number of incidents studied); characteristics of violence (assaults, murders, sexual assaults, suicides, robbery, collective Volume 27, Supplement: November 2026

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Rising Ambient Temperatures and Their Association with Increased Violence inclusion criteria, leaving us with 73 articles for retrieval. We reviewed 71 full texts for eligibility as two could not be retrieved. Of these 71 articles, we excluded five systematic reviews, 11 non-peer reviewed articles, and 18 articles that did not describe the effect of temperature on violence, leaving a total of 37 articles to be included in the final review5-41 (Table 1). The process of screening and selecting studies is shown in the PRISMA flow diagram (Figure 1).

Of 37 studies, 28 reported absolute incident counts for various forms of violence (Table 3). The aggregated totals from these studies were as follows: • Assaults: 5,590,523 incidents (across 12 studies) • Suicides: 468,905 incidents (across 7 studies) • Collective violence: 133,500 incidents (across 4 studies) • Firearm-related incidents: 273,377 incidents (across 2 studies) • Intimate partner violence: 164,123 incidents (across 4 studies)

Study Characteristics In our final analysis we included 37 studies from 11 countries (Australia, Belgium, Italy, USA, Switzerland, Hong Kong, South Korea, UK, Taiwan, Spain, and Finland), three subcontinental regions, and two global-level studies (Table 1). Among these, the USA accounted for the largest proportion, with 17 studies (46%), followed by the UK with three studies, and Italy, Australia, and Belgium with two studies each. Interpersonal assaults were the most frequently analyzed dependent variable—examined in 16 studies— followed by suicides involving violent methods in eight studies. Firearm violence, collective violence (riots or civil wars), and intimate partner violence (IPV) were each analyzed in four studies (Table 1). The number of studies exploring the association between temperature and specific forms of violence was as follows: homicides (10 studies); assaults (15 studies); IPV (9 studies); sexual assaults (8 studies); suicides (9 studies), robbery (7 studies); firearmrelated violence (5 studies); and civil wars and riots (2 studies each) (Table 2).

Definitions Violent Crime The term violent crime encompasses a range of offenses as defined by the authors, including murder, assault, sexual assault, robbery, firearm-related violence, suicides, domestic violence, civil wars, and conflicts. Non-violent and Violent Suicides Suicides were classified based on International Classification of Diseases, 9th Rev (ICD-9) codes. Non-violent suicides (ICD-9 codes E950–E952) include those caused by poisoning with solids, liquids, gases, or vapors. All other forms of suicides were categorized as violent suicides (ICD-9 codes E953–E959). Temperature The measurement of temperature variations showed significant heterogeneity in the timeframes used across studies. The timeframes included 17 daily measurements, 10 monthly measurements, three 3- or 6-hourly intervals, three yearly measurements, two measurements at quarterly intervals, one at 6-monthly intervals, and one that recorded weekly measurements (Table 1). Outcome Analysis: Effect of Temperature on Violence All 37 studies used standard statistical methods to assess the relationship between temperature and violence. Of these, 36 studies reported a positive association between rising ambient temperatures and violence, including both self-harm and interpersonal violence. The one study that did not identify a positive association was hospital-based, focusing on assaultrelated Accident & Emergency Department visits. This study may not accurately reflect the true extent of violence occurring in the broader community.37 The studies summarized their data differently making it difficult for us to pool the data for a meta-analysis. However, eight studies that reported the risk of increase in violence for each degree Celsius rise of ambient temperature were pooled in the meta-analysis (Figure 2). Homicides (Table 3) The association between temperature and homicides was explored in 10 studies conducted over a cumulative 117 years in four countries: the USA (seven studies), Finland, Australia,

Figure 1. PRISMA flow diagram for the systematic review of association of ambient temperature with violence.

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Table 1. Characteristics of the included studies in the systematic review of the association between temperature and violence.5-41 First Author

Sample Period

Anderson CA;1987 Anderson CA;1984

Temperature Time unit

Spatial unit

Main variable

JBI Score

Daily

City

Assault

Quarterly

Country

Assault

Country

Assault

Country

Suicides

Daily

State

Assault

Global

Yearly

Country

Riot/Civil War

USA

Daily

Country

Riot/Civil War

HongKong

Monthly

SAR

Suicides

USA

Daily

City

Assault

USA

Daily

County

Firearm violence

South Korea

Daily

Country

Assault

2008-19

Australia

Quarterly

State

Assault

1999-2012

USA

Daily

City

Firearm violence

Daily

County

Assault

Taiwan

Monthly

Country

Suicides

Belgium

Monthly

Country

Suicides

USA

Daily

Country

Firearm violence

Belgium

Weekly

Country

Suicides

Monthly

City

Assault

Monthly

Country

IPV

USA

Monthly

Country

IPV

USA

Daily

City

Assault

Daily

City

Assault

East Africa

6-Monthly

Sub-Continent

Riot/Civil War

Sub-Saharan Africa

Monthly

Sub-Continent

Riot/Civil War

1984-95

Italy

Monthly

Country

Suicides

1984-95

Italy

Monthly

Country

Suicides

Rotton J;1985

1975-76

USA

Daily

City

Assault

Rotton J;2000

1994-95

USA

3-hourly

City

Assault

Rotton J;2001

1987-88

USA

6-hourly

City

IPV

Ruderman D;2021

2014-19

USA

Daily

Country

Firearm violence

Sanz-Barbero B;2018

2008-16

Spain

Daily

City

IPV

Sivarajasingam V;2004

1995-2000

Monthly

City

Assault

Stevens HR;2024

2013-18

Australia

Daily

City

Assault

Tiihonen J;2017

1996-2013

Finland

Monthly

Country

Assault

Zhou X;2024

1990-2019

Global

Yearly

Global

Suicides

Zhu Y;2023

2010-18

South Asia

Daily

Sub-Continent

IPV

Years

Region

1980-82

USA

1971-80

USA

Anderson CA;1997

1950-95

USA

Yearly

Bar S;2022

1995-2016

Switzerland

Daily

Basu R;2018

2005-13

USA

Bolfrass A;2015

1994-2014

Carlsmith JM;1979

1967-71

Chau PH;2020

1976-2014

Cook MR;2012

2008-09

Dana EG;2018

2007-11

Heo S;2024

2016-20

Hodgkinson T;2023 Jude Kieltyka;2016 Lemon DJ;2017

2014-16

Lin HC;2008

1997-2003

Linkowsky P;1992

1969-84

Lyons VH;2022

2015-20

Maes M;1994

1979-87

Mares D;2013

1990-2009

USA

Michael RP;1983

1981-84

USA

Michael RP;1986

1975-79

Michel SJ;2016

2008-13

Moore SC;2022

2016-19

O’Loughlin J;2014

1990-2009

O’Loughlin J;2012

1980-2012

Preti A;1998 Preti A;2000

JBI, Joanna Briggs Institute quality assessment score; USA, United States of America; UK, United Kingdom; SAR, Special Administrative Region; IPV, intimate partner violence.

and South Korea (one study each).5-7,9,15,23,24,26,38,39 The studies were carried out at the country (five studies), state (one study), and city levels (four studies), with temperature measured in the context of a yearly timeframe in one study, quarterly in one study, monthly in three studies, and daily timeframes in five studies. All 10 studies demonstrated a significant positive Volume 27, Supplement: November 2026

association between higher ambient temperatures and increased homicide rates. Assaults (Table 3) Fifteen studies analyzed the relationship between temperature and assaults over a combined duration of 160 years. These studies spanned eight cities, six countries, one 23

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Table 2. Types of violence reported by the studies included in a systematic review of the association between temperature and violence.5-41 First author

Years

Region

Temperature time unit

Spatial unit

Dependent variables

Anderson CA;1987

USA

Daily

City

Homicide, Assault, Rape, Robbery, Theft

Anderson CA;1984

USA

Quarterly

Country

Homicide, Rape, Robbery, Theft

Anderson CA;1997

USA

Yearly

Country

Homicide, Assault, Rape, Robbery, Property Crime

Bar S;2022

Switzerland

Daily

Country

Suicide

Basu R;2018

USA

Daily

State

Homicide, Psychosis, Neurosis, Self-injury/Suicide

Bolfrass A;2015

Global

Yearly

Country

Civil War

Carlsmith JM;1979

USA

Daily

Country

Riot

Chau PH;2020

Hong Kong

Monthly

SAR

Suicide (violent and non-violent)

Cook MR;2012

USA

Daily

City

Assault

Dana EG;2018

USA

Daily

County

Firearm violence

Heo S;2024

South Korea

Daily

Country

Homicide, Assault, Robbery, IPV

Hodgkinson T;2023

Australia

Quarterly

State

Assault, Rape, Robbery, IPV

Jude Kieltyka;2016

USA

Daily

City

Firearm violence

Lemon DJ;2017

Daily

County

Assaults

Lin HC;2008

Taiwan

Monthly

Country

Suicide (violent and non-violent)

Linkowsky P;1992

Belgium

Monthly

Country

Suicide (violent and non-violent)

Lyons VH;2022

USA

Daily

Country

Firearm violence

Maes M;1994

Belgium

Weekly

Country

Suicide (violent)

Mares D;2013

USA

Monthly

City

Homicide, Assault, Rape, Robbery

Michael RP;1983

USA

Monthly

Country

Homicide, Assault, Rape, Robbery

Michael RP;1986

USA

Monthly

Country

IPV

Michel SJ;2016

USA

Daily

City

Homicide, Assault, Rape, Firearm Violence

Moore SC;2022

Daily

City

Assault

O’Loughlin J;2014

East Africa

6-Monthly

Sub-Continent Riot

O’Loughlin J;2012

Sub-Saharan Africa

Monthly

Sub-Continent Civil War

Preti A;1998

Italy

Monthly

Country

Suicide (violent and non-violent)

Preti A;2000

Italy

Monthly

Country

Attempted suicide (violent, non-violent)

Rotton J;1985

USA

Daily

City

Assault

Rotton J;2000

USA

3-hourly

City

IPV

Rotton J;2001

USA

6-hourly

City

Assault, IPV

Ruderman D;2021

USA

Daily

Country

Firearm violence

Sanz-Barbero B;2018

Spain

Daily

City

IPV

Sivarajasingam V;2004

Monthly

City

Assault related A&E admissions

Stevens HR;2024

Australia

Daily

City

Homicide, Assault, Rape, IPV

Tiihonen J;2017

Finland

Monthly

Country

Homicide, Assault

Zhou X;2024

Global

Yearly

Global

Attempted suicide, IPV

Zhu Y;2023

South Asia

Daily

Sub-Continent IPV

USA, United States of America; UK, United Kingdom; SAR, Special Administrative Region; IPV, intimate partner violence; A&E, Accident and Emergency Department.

state, and one at a global level.5, 7, 13, 15, 16, 18, 23, 24, 26, 27, 33, 34, 37-39 Temperature variations were recorded at the following intervals: at 3-hour intervals in one study; daily in seven studies; monthly in four studies; quarterly in two; and yearly in two studies. All studies, except one that focused on a single hospital’s assault-related visits, found a Western Journal of Emergency Medicine

significant association between rising temperatures and increased assaults.37 Sexual Assaults (Rape) (Table 3) Eight studies investigated the link between rising temperatures and sexual assaults over a cumulative 100 years, six studies in the USA and two in Australia.5-7, 16, 23, 24, 26, 24

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Table 3. Incidents of violence as reported by the studies included in the systematic review of the association between temperature and violence. First author

Sample period

Region

Main dependent variable

Incidents

Basu R;2018

2005-13

USA

Assault

1,041,433

Cook MR;2012

2008-09

USA

Assault

414

Heo S;2024

2016-20

South Korea

Assault

414,6474

Hodgkinson T;2023

2008-19

Australia

Assault

4,380

Lemon DJ;2017

2014-16

Assault

4,262

Michel SJ;2016

2008-13

USA

Assault

32,654

Rotton J;1985

1975-76

USA

Assault

18,687

Rotton J;2000

1994-95

USA

Assault

57,834

Sivarajasingam V;2004

1995-2000

Assault

19,264

Stevens HR;2024

2013-18

Australia

Assault

182,962

Tiihonen J;2017

1996-2013

Finland

Assault

55,159

Bolfrass A;2015

1994-2014

Global

Riot/Civil War

44,498

Carlsmith JM;1979

1967-71

USA

Riot/Civil War

102

O’Loughlin J;2014

1990-2009

East Africa

Riot/Civil War

72,541

O’Loughlin J;2012

1980-2012

Sub-Saharan Africa

Riot/Civil War

16,359

Jude Kieltyka;2016

1999-2012

USA

Firearm violence

156,866

Lyons VH;2022

2015-20

USA

Firearm violence

116,511

Rotton J;2001

1987-88

USA

IPV

10,765

Sanz-Barbero B;2018

2008-16

Spain

IPV

38.088

Michael RP;1983

1975-79

USA

IPV

27,000

Zhu Y;2023

2010-18

South Asia

IPV

52,567

Bar S;2022

1995-2016

Switzerland

Suicides

24,067

Chau PH;2020

1976-2014

Hong Kong

Suicides

7,944

Lin HC;2008

1997-2003

Taiwan

Suicides

18,130

Linkowsky P;1992

1969-84

Belgium

Suicides

25,075

Preti A;1998

1984-95

Italy

Suicides

43,755

Preti A;2000

1984-95

Italy

Suicides

27,456

USA, United States of America; UK, United Kingdom; IPV, intimate partner violence.

Data were collected in three studies at the country level, one at the state level, and four at the city level, with temperature in three studies recorded daily, monthly in two studies, quarterly in two studies, and yearly in one study. All studies identified a significant increase in sexual assaults with higher ambient temperatures.

and one each represented Spain, South Korea, and South Asia), with data collected in four studies at the city level, two at the country level, and one each at regional and state levels. In one study, temperature was recorded at 6-hour intervals, while temperature was recorded in five studies on a daily basis, and one study each recorded temperature at quarterly and monthly intervals. Seven studies provided actual numbers, reporting a total of 1,797,812 incidents. All nine studies showed a significant positive association between temperature and IPV.

Firearm Violence (Table 3) Five studies from the USA analyzed firearm violence over a combined 32 years, using daily temperature measurements.14, 17, 21, 26, 35 Data were collected in three studies at the country level and two studies at city levels. All studies found a significant positive association between rising daily temperatures and increased firearm violence. Domestic or Intimate Partner Violence (IPV) (Table 3) Nine studies, spanning 41 years, examined the association between ambient temperatures and IPV.15, 16, 25, 32, 34, 36, 38, 40, 41 Three studies represented the USA, two represented Australia, Volume 27, Supplement: November 2026

Suicides (Table 3) Nine studies conducted over a cumulative 147 years examined the relationship between temperature and suicides in six countries, and one study examined that relationship globally.8, 9, 12, 19, 20, 22, 30, 31, 40 Temperature was measured daily in two studies, weekly in one study, monthly in five studies, and yearly in one study. Seven studies reported a total of 468,905 suicide incidents, categorizing them as violent (ICD-9 codes 25

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Figure 2. Meta-analysis of eight studies that reported risk of increased violence for each degree Celsius rise in ambient temperature. Based on the investigations performed using a random effects model with inverse variance method, a statistically significant effect can be observed. The summarized effect of each degree Celsius rise of temperature was an increase in violence by 1.64% with a 95% confidence interval of 1.23-2.19. The test for overall effect verified a statistically significant P value <.01. A significant heterogeneity was spotted (P<.01), suggesting fluctuating effects in extent and/or direction. The I2 value shows that 100% of the inconsistency among the cohorts originates from heterogeneity rather than random chance.

E953–959) or non-violent (ICD-9 codes E950–952). All studies found a significant association between rising temperatures and suicides, with two reporting an effect on only violent suicides, while one found a link to both types.

Psychiatric Illnesses (Table 3) One study examined the link between temperature and psychiatric illnesses presenting to hospitals.9 A 10°F increase in temperature during summer resulted in the following: psychosis, +2.9% (0.7-5.2); neurosis, +5.3% (3.8-7.6); self-injury, +5.8% (4.5-7.1); and inflicted injuries: +7.9% (7.3-8.4). During winter, the same temperature increase led to these results: psychosis, +3.9% (1.6-6.3); neurosis, +6.0% (4.5-7.5); self-injury, +7.2% (5.7-8.8); and inflicted injuries, +10.6% (9.8-11.4). The study found a significant association between ambient temperatures and psychiatric illnesses, with a stronger effect observed in winter.

Civil Wars (Table 3) Two studies examined temperature and civil wars.10, 29 One analyzed global incidents over 20 years, with yearly temperature variations, while the other focused on East Africa over 19 years, with 6-monthly temperature data. Both studies reported a significant association between higher temperatures and an increase in civil war incidents. Riots (Table 3) Two studies explored the relationship between temperature and riots.11, 28 One study in the USA used four years of daily temperature data, while the other, from SubSaharan Africa, spanned 32 years using monthly temperature variations. Both studies showed a significant positive association between high temperatures and riots.

DISCUSSION Rising global temperatures, along with other effects of climate change, have shown a clear and significant impact on human health. Various issues such as vector-borne and infectious diseases, environmental pollution hazards, injuries due to natural disasters, allergies, respiratory illnesses, malnutrition, and the mental health impacts of disasters are well-documented concerns.42 However, one critical health issue often overlooked is the relationship between global warming and violence. This systematic review highlights the significant influence of rising temperatures on incidents of violence worldwide. Violence is commonly defined as an act of physical force intended to cause harm and can be broadly categorized into interpersonal violence and group conflicts. Interpersonal violence includes homicides, assaults, sexual assaults, IPV, and firearm violence, while group conflicts cover riots and

Non-Violent Crimes (Table 3) Non-violent crimes, including robbery, arson, theft, and property crimes, were analyzed by Anderson CA et al between 1971–1995 in the USA.5-7 Using daily, quarterly, and yearly temperature data, the study found no significant association between ambient temperature and non-violent crimes. Trauma Center Admissions (Table 3) Four studies found that trauma center admissions following assaults increased with rising temperatures, while one study reported no significant association.9, 13, 14, 26, 37 Western Journal of Emergency Medicine

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civil wars. Our review demonstrates that rising ambient temperatures are significantly associated with an increase in homicides, assaults, sexual assaults, IPV, and firearm violence. This relationship was observed across various timeframes of temperature measurement—daily, weekly, monthly, quarterly, and yearly—and across a wide range of global communities. Our meta-analysis of eight studies on violence showed that each 1°C increase in ambient temperature results in 1.64% (95% confidence interval 1.23-2.19%) increase in violence (P<.01). Hsiang et al quantified the effect of climate on violence, finding that each one standard deviation increase in temperature results in a 4% increase in interpersonal violence and a 14% increase in intergroup conflict.43 Projections suggest that, by the end of the century, climate change could result in an additional 22,000 homicides, 1.2 million aggravated assaults, and 2.3 million simple assaults in the United States alone compared to 2010.44 Interestingly, temperature appears to primarily influence violent crimes, such as assaults and homicides, while non-violent crimes, such as robbery, arson, and property crimes, remain unaffected.5-7 Similarly, studies show a significant rise in violent suicides associated with higher temperatures but no such effect on non-violent suicides, such as those involving poisoning.9, 12, 19, 20, 22, 30, 31, 40

mental health crises, and self-harm.9, 13, 14, 26, 31, 37 Targeted police interventions, informed by spatiotemporal analysis, have proven effective in mitigating violence in high-risk areas without displacing the issue to other regions.13 Advanced warning systems for heat waves and hotter days can enable hospitals to expect increased arrivals of patients due to violence. However, the extra numbers of arrivals may still be too small to meaningfully impact the needed staffing and resources that should be scheduled to address the increased number of violence-related emergencies that could be anticipated. Temperature and Mental Health While lunar cycles have long been associated with mental health (eg, the term “lunatic”), studies have found no substantial link between lunar phases and psychiatric admissions or discharges.47 Conversely, the relationship between temperature and mental health is well-established.9 A 10°F (5.6°C) increase in mean apparent temperature during warm seasons correlates with increases in emergency visits for the following: mental health disorders (+4.8%); self-injury/ suicide (+5.8%); and intentional injuries/homicides (+7.9%), Intimate partner violence rates are consistently higher on hotter days, even when partner interactions remain constant throughout the year. Zhu et al estimated that a 1°C increase in annual mean temperature results in a 4.49% increase in IPV prevalence.25

The Mechanisms Behind Temperature-Aggression The General Aggression Model (GAM) provides a framework for understanding human responses to provoking situations. It suggests that a person’s reaction—thoughtful or impulsive—depends on their internal state, influenced by affect, cognition, and arousal.2 For example: • Affect: Discomfort or pain increases anger and hostility. • Cognition: Media or social priming can condition individuals to be more violent. • Arousal: Situational arousal, such as from exercise, can amplify aggression in response to provocation (a concept explained by the excitation transfer theory). High temperatures, as per the temperature-aggression hypothesis, lead to discomfort that heightens aggression across all three domains of GAM. This increases the likelihood of impulsive violent behaviors, even with minimal provocation.45 In regions where warm temperatures are not inherently uncomfortable, the routine activity theory offers an alternate explanation. It says that warmer temperatures encourage outdoor activities and social interactions, thereby increasing the likelihood of interpersonal conflicts and exposure to crimeprone environments.46

Need for Research and Interventions Despite growing evidence linking temperature to violence, there is limited research on mitigating its effects through heat warning systems and public health strategies. Policymakers and researchers must prioritize developing novel interventions aimed at reducing aggression and violence during hotter days. These could include the following: • Community-level public health campaigns to “cool tempers” during heatwaves. • Enhanced preparedness for hospitals and police during extreme weather events. • Investigation of technologies and policies to create safer environments amid climate change. As global temperatures continue to rise, addressing this under-recognized public health concern is crucial to protecting communities and reducing the societal impacts of climate change. LIMITATIONS The included studies vary in terms of locations, timeframes, and methods for measuring temperature and violence, limiting generalizability across different regions and cultures. Many studies may not have controlled for other factors such as socioeconomic status, urbanization, or social tensions, which could influence both temperature sensitivity and violence rates. Most studies are cross-sectional, and the scarcity of longitudinal data makes it difficult to establish causal relationships between

Implications for Public Health and Safety Higher ambient temperatures place significant burdens on hospitals and emergency services as they deal with increased cases of heat-related injuries, trauma, assault, Volume 27, Supplement: November 2026

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Rising Ambient Temperatures and Their Association with Increased Violence temperature increases and violence over time. Most studies come from high-income countries, especially the USA and Europe, with fewer from low- and middle-income regions, which limits the applicability to global populations. Differences in how violence is defined and measured across studies, including official crime statistics vs hospital admissions, may result in discrepancies and fail to capture all forms of violence. Despite these limitations, the review highlights important trends and calls for more targeted research to better understand the link between temperature and violence.

Chauhan et al.

2. Allen JJ, Anderson CA, Bushman BJ. The General Aggression Model. Curr Opin Psychol. 2018;19:75-80. 3. Liberati A, Altman DG, Tetzlaff J, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS med. 2009;6(7):e1000100. 4. Munn Z, Moola S, Lisy K, et al. Chapter 5: Systematic Reviews of Prevalence and Incidence. 2019. Available at: https://www. researchgate.net/publication/342593810_Chapter_5_Systematic_ Reviews_of_Prevalence_and_Incidence. Accessed March 15, 2023. 5. Anderson CA. Temperature and aggression: effects on quarterly,

CONCLUSION This systematic review highlights a statistically significant relationship—of a small but detectable effect size—between rising ambient temperature and an increase in violence, including homicides, assaults, sexual assaults, suicides, intimate partner violence, firearm violence, riots, and civil wars. Violent behaviors, both interpersonal and group conflicts, are clearly influenced by ambient temperature increases, while non-violent crimes remain largely unaffected. Our findings emphasize the growing burden on hospitals, law enforcement, and public health systems during heat-related emergencies, including violence-related injuries and mental health crises. Targeted interventions, spatiotemporal analysis of hotspots, and early preparedness during extreme heat events are appropriate mitigation steps. As global temperatures continue to rise, integrating violence prevention into broader climate-adaptation frameworks is an appropriate consideration. Focused research and public health strategies are needed to mitigate the behavioral and societal challenges posed by climate change.

yearly, and city rates of violent and nonviolent crime. J Pers Soc Psychol. 1987;52(6):1161-73. 6. Anderson CA, Anderson DC. Ambient temperature and violent crime: tests of the linear and curvilinear hypotheses. J Pers Soc Psychol. 1984;46(1):91-7. 7. Anderson CA, Bushman BJ, Groom RW. Hot years and serious and deadly assault: empirical tests of the heat hypothesis. J Pers Soc Psychol. 1997;73(6):1213-23. 8. Bär S, Bundo M, de Schrijver E, et al. Suicides and ambient temperature in Switzerland: a nationwide time-series analysis. Swiss Med Wkly. 2022;152:w30115. 9. Basu R, Gavin L, Pearson D, et al. Examining the association between apparent temperature and mental health-related emergency room visits in California. Am J Epidemiol. 2018;187(4):726-35. 10. Bollfrass A, Shaver A. The effects of temperature on political violence: global evidence at the subnational level. PloS one. 2015;10(5):e0123505. 11. Carlsmith JM, Anderson CA. Ambient temperature and the occurrence of collective violence: a new analysis. J Pers Soc Psychol. 1979;37(3):337-44. 12. Chau PH, Yip PSF, Lau HYE, et al. Hot weather and suicide deaths

Address for Correspondence: Vivek Chauhan, MD, Indira Ghandi Medical College, Department of Medicine, Shimla, Indira Gandhi Medical College, Shimla, Himachal Pradesh, India, 171001. Email: drvivekshimla@yahoo.com.

among older adults in Hong Kong, 1976-2014: a retrospective study. Int J Environ Res Public Health.2020;17(10). 13. Cook MR, Emick D, Foley C, et al. Daily temperature predicts assault and may allow more efficient policing. Am Surg. 2012;78(4):E194-5.

Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliaions, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare.

14. Dana EG, Kara ER, Jennifer A. Predictors of firearm violence in urban communities a machine learning approach. Health Place. 2018;51:61-7. 15. Heo S, Choi HM, Lee JT, et al. A nationwide time-series analysis for short-term effects of ambient temperature on violent crime in South Korea. Sci Rep. 2024;14(1):3210.

Copyright: © 2025 Chauhan et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

16. Hodgkinson T, Corcoran J, Andresen MA. Violent assault geographies in northeastern Australia. PloS one. 2023;18(3):e0282522. 17. Kieltyka J, Kucybala K, Crandall M. Ecologic factors relating to firearm injuries and gun violence in Chicago. J Forensic Leg Med. 2016 Jan;37:87-90.

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Original Research

Impact of Daily Maximum Temperature on Emergency Department Arrivals and Acuity Levels Catharina Giudice, MD, MPH*† Nicholas J. Arisco, PhD‡ Zilin Lu, MPH§ Bryan Stenson, MD* Caleb Dresser, MD, MPH*†

*Beth Israel Deaconess Medical Center, Department of Emergency Medicine, Boston, Massachusetts † Harvard T.H. Chan School of Public Health, Harvard Chan Center for Climate, Health and the Global Environment, Department of Environmental Health, Boston, Massachusetts ‡ Harvard T.H. Chan School of Public Health Department of Global Health and Population, Boston, Massachusetts § Tufts University, Department of Public Health and Community Medicine, Boston, Massachusetts

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted February 6, 2025; Revision received May 2, 2025; Accepted May 12, 2025 Electronically published September 25, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.42263

Introduction: Heatwaves are becoming more frequent and severe globally. Heat is associated with increases in emergency department (ED) volumes and higher morbidity for a range of chronic conditions. We describe how temperature impacts ED arrivals at different acuity levels. Methods: We obtained time-series records for daily ED arrivals stratified by Emergency Severity Index (ESI) from 2010 – 2019 from hospital records. Wet-bulb temperature was the exposure of interest; analysis was controlled for precipitation, snow, wind speed, day of week, and federal holidays. We fitted a Poisson model for each ESI category and estimated the association between temperature and ED arrival acuity with a distributed lag non-linear model with three days of lag to account for delayed health effects of temperature. Results: We analyzed data for 3,652 days totaling 556,663 arrivals between 2010 – 2019. At lag 0, lower temperatures were associated with a reduced relative risk of arrival to the ED for ESI 2, ESI 3, and total arrivals. At higher temperatures, ESI 2 and ESI 3 showed an increased relative risk of arrival (wet-bulb exposure of 25°C at 0-day lag: ESI 2 RR = 1.06 [1.02–1.10]; ESI 3 RR = 1.04 [1.011.07]). While not statistically significant, ESI 1 exhibited a subtle increase in arrivals at the highest temperatures while ESI 4 & 5 displayed a subtle decrease in relative risk of arrivals under these conditions. Conclusion: Extremes of temperature, particularly heat, appear to affect ED arrivals differently across different acuity levels. Medium- to higher-acuity presentations appear to be more responsive to heat, with a statistically significant increase in ED presentations on days with the highest heat burden. The highest acuity presentations became numerically but not statistically more frequent on days with the highest heat burden, while the lowest acuity presentations decreased numerically but not statistically in these conditions. [West J Emerg Med. 2025;27(6.1)30–36.]

INTRODUCTION Climate change is becoming an increasingly important determinant of health, with potential operational implications for acute care systems. The global annual average temperature for 2024 has already surpassed pre-industrial era levels by 1.6 ℃1 Western Journal of Emergency Medicine

and, under the most optimistic scenarios, are expected to exceed 2.7 ℃ during the 21st century.2 Episodes of extreme heat are becoming more frequent, prolonged, and extreme throughout the United States. By midcentury, heat indexes exceeding 37.8 ℃ are expected to triple in the Northeast under an intermediate 30

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greenhouse gas emission scenario.3 This has profound implications for health and healthcare delivery, including increases in all-cause mortality, healthcare utilization, rates of death from cardiovascular and respiratory diseases,4 mental health issues,5 accidental and non-accidental trauma,6 and adverse birth outcomes.7 Broadly, heat is known to be a significant environmental contributor to mortality. Emergency departments (ED), as the primary access point for acute healthcare delivery, also face increases in volume and operational burden due to extreme heat.8 Previous studies have shown a relationship between higher temperatures and increased overall ED use.8,9 However, there is wide variation in the disease severity of patients presenting to EDs and the level of resources required to provide appropriate care. Few studies have looked at how temperature and other environmental variables affect the acuity level of emergency arrivals.10-13 At a facility level, understanding how heat impacts patient presentations across each of the five Emergency Severity Index (ESI) levels may facilitate more informed resource allocation and staffing decisions. At a community level, knowledge of the range of pathologies for which patients seek care during extreme heat may inform policies and programs intended to preserve health and reduce burden on acute care systems. Our aim in this study was to evaluate relationships between ambient temperature and ED arrival volume across the spectrum of acuity at an urban hospital in the Northeastern US.

Population Health Research Capsule What do we already know about this issue? Heat is a significant environmental contributor to mortality and has been shown to increase overall emergency department (ED) utilization. What was the research question? Does the temperature responsiveness of ED arrivals differ by case acuity level? What was the major finding of the study? Heat (25 °C) increased ED arrivals for Emergency Severity Index (ESI) 2 (RR=1.06 [1.02–1.10]) and ESI 3 (RR=1.04 [1.01– 1.07]). How does this improve population health? Understanding the impact of extreme heat on ED arrivals informs data-driven climate preparedness and may guide staffing and resource planning during heat waves. .

METHODS Setting This study was completed at an urban, academic medical center in the Northeast region of the US with an annual ED volume of approximately 55,000 patients per year. We chose the study period 2010 – 2019 to exclude the COVID-19 pandemic, during which ED visits did not follow typical volume patterns. The predominant climate in the study region is humid subtropical, characterized by hot, humid summers and an average snowfall of 50 inches during the winter months. Thunderstorms are common from June–August.14

for Environmental Information. Boston Logan International Airport Station (WBAN:14739) was selected due to its proximity to the study site (8.5 km). Federal holidays occurring during the study period were obtained from government historical records. There is evidence suggesting equivalence between different temperature metrics used to assess heat exposure in population health research.16 For this study, we chose wet-bulb daily maximum temperature as the exposure index, as it combines both ambient temperature and humidity and may better correlate with physiological response to heat.

Data Sources We obtained daily ED arrivals stratified by ESI from 2010–2019 from electronic health records (EHR) at a large, urban hospital. The ESI is a five-level scale used to assess patient stability, risk of deterioration, and anticipated resource needs.15 An ESI 1 is assigned to patients with severe medical conditions requiring immediate lifesaving interventions, while ESI 5 is assigned to patients who are stable and expected to require minimal resources for care. Due to the relatively low volume of patients in the ESI 4 and ESI 5 categories and their similar relative clinical stability and low resource needs, we combined these two groups in this analysis. We obtained historic weather records from the National Oceanic and Atmospheric Administration, National Centers

Statistical Analysis We performed a Poisson regression time series analysis using a framework of distributed lag nonlinear models (DLNM) to estimate the effect of temperature (℃) on ED arrival volumes for each ESI category. Model specification and choice of control variables were based on prior ED arrival predictive modeling studies.17 We included several control variables, including daily precipitation (millimeters [mm]), wind speed (meters per second), snow (mm), day of the week, day of holiday, day before holiday, and day after holiday. Our exposure of interest was wet-bulb daily maximum temperature, which was modeled using a cubic B-spline with 2 degrees of freedom to account for seasonality and long-term trends in accord with previous studies.18,19 To evaluate for a possible “lag” effect, which is to

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Impact of Daily Maximum Temperature on ED Arrivals and Acuity Levels say, to evaluate for the possibility that the influence of temperature extremes are most pronounced on one of the days subsequent to the day of the temperature extreme, we evaluated the influences of lags of 0, 1, 2, and 3 days.20 Lags were modeled using a cubic B-spline with 4 degrees of freedom. Wind speed was controlled for the day of ED arrival. To evaluate the possibility that the influence of snow and precipitation are most pronounced on one of the days after these events, we evaluated the influence of lags of 0, 1, and 2 days. In the cross-basis function, three internal knots were placed at the 10th, 50th, and 90th percentiles for each environmental variable. We defined the median value of temperature (11.7℃) as the baseline temperature or centering value for calculating the relative risk (RR). We plotted the RR against temperature for each lag and for all lags aggregated. We conducted sensitivity analysis to test the robustness of changing model choices for daily lagged models, using average and minimum temperature instead of maximum temperature as the primary exposure, and altering the exposure variable choice to include dry-bulb temperature and humidity (Appendix). We used Akaike information criteria values to help guide model selection. All analysis was performed with R software v4.3.2 (R Foundation for Statistical Computing, Vienna, Austria) using package DLNM (v2.4.7) for the distributed lag nonlinear model.

Giudice et al.

Figure 1. Box plot of total emergency department arrivals per day stratified by Emergency Severity Index category. ED, emergency department; ESI, Emergency Severity Index.

Ethics This study was approved by the Committee on Clinical Investigations at Beth Israel Deaconess Medical Center (institutional review board) Protocol 2022P000002). RESULTS The dataset included 3,652 days and totaled 556,663 arrivals during the study period from 2010 – 2019. The ESI 3 group accounted for the greatest number of arrivals at 297,074 (53%), followed by ESI 2 at 178,031 (32%), ESI 4 and 5 combined at 42,086 (7.6%), and ESI 1 at 39,472 (7.1%) (Figure 1). When aggregated over the study period, total ED arrivals were highest on Mondays and in July, and lowest on Sundays and in February, aligning with established trends in ED volume. Daily time series stratified by ESI indicate a high degree of variability across all ESI groups, without obvious cyclical patterns (Figure 2). Daily maximum wet-bulb temperature for the study period ranged from -13.8 °C to 27.2 °C with a mean of 10.8 °C (SD 8.6 °C). Figure 3 shows the cumulative exposure-response curves for the different ESI categories with relative risk of 1 set at the median maximum temperature for the study period (11.7 °C). The temperature distribution highlights how, at the extremes of the temperature range, only a small number of hot or cold days occur. At lag 0, lower temperatures were associated with a reduced RR of arrival to the ED for ESI 2, ESI 3, and total arrivals. At higher temperatures, ESI 2, ESI 3, and total arrivals showed an increased RR of arrival. ESI 1 and ESI 4 & 5 did not demonstrate a statistically significant association with temperatures across most temperature ranges. Western Journal of Emergency Medicine

Figure 2. Daily time series of ED arrival for each Emergency Severity Index category and maximum wet-bulb temperature for the study period. ED, emergency department; ESI, Emergency Severity Index.

On the hottest 5% of days, there was a small numeric increase in the RR of higher acuity arrivals (ESI 1 and ESI 2) and a small numeric decrease in RR of lower-acuity presentations (ESI 3 and ESI 4 & 5), but these effects did not 32

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Impact of Daily Maximum Temperature on ED Arrivals and Acuity Levels accounting for lags and non-linear patterns.10-13 Here, we address this gap by employing a distributed lag non-linear Poisson regression to account for seasonality and the delayed health effects of heat across each acuity strata. Total ED arrivals (aggregated across strata of acuity) increased with temperature, consistent with findings from other studies using EHR or claims data.8,21-23 When stratified by acuity, DLNMs revealed that most of the temperatureresponsiveness of ED arrivals was in medium- to high-acuity cases (ESI 2 and ESI 3). Arrivals in these groups increased with temperature, even at temperatures well below the threshold typically associated with heat-related illness (HRI). During the hottest 5% of days, our data suggest that RR for ESI 2 arrivals continues to increase, whereas for ESI 3, the RR returns toward baseline. The highest acuity (ESI 1) and lowest acuity (ESI 4 & 5) cases did not demonstrate statistically significant associations with temperature. However, on the hottest 5% of days, ESI 1 arrivals exhibited a subtle numeric increase in RR of arrivals with increasing temperature, while ESI 4 and 5 displayed a subtle numeric decrease in RR of arrivals on the hottest days. At this temperate-zone site, most heat-related illness cases are expected to occur within the upper 10% of temperatures. It is plausible that very hot weather could influence decisions to seek or not seek care for low-acuity conditions. While caution is warranted when interpreting these edge cases, the opposing directions in the upper tails of the DLNM curves at the highest temperatures—an upward numeric change for higher acuity cases and downward numeric change for lower acuity cases— are suggestive of different dynamics affecting heat-sensitive pathologies and/or care-seeking behavior between high- and low-ESI groups. These findings warrant further investigation using larger datasets and/or at sites with higher levels of heat exposure. With regard to the lagged impact of temperature, we found the overall strongest effect on current day of exposure (lag 0), which aligns with current literature,24-26 although some heterogeneity existed between different ESI groups. While additional studies, particularly in regions experiencing a higher frequency of extreme temperature days, will help clarify the relationship between temperature and the acuity of ED arrivals, the numeric effects noted in this study are worth examining. For instance, heat may increase the risk of decompensation of chronic conditions in addition to leading to cases of heatstroke or heat exhaustion, driving higher numeric RR values of high-acuity presentations in the hottest weather. This hypothesis aligns with existing literature that describes extreme heat as a driver for higher morbidity of cardiovascular, respiratory, renal, and psychiatric pathologies, which frequently lead to higher acuity arrivals.4-6,9 Conversely, for lower acuity presentations, adverse weather conditions may deter careseeking behaviors, contributing to lower numeric RR of presentation. Interestingly, prior epidemiologic studies exploring the mortality-temperature relation have suggested a U- or J-shaped exposure-response curve,19, 27 where both high

Figure 3. Relative risk (RR) of emergency department presentation in relation to daily maximum temperature at lag 0, stratified by Emergency Severity Index (ESI) category. Solid line is the exposure-response curve (best linear unbiased prediction) with 95% confidence interval (CI) shaded in light red (ESI 1), orange (ESI 2), yellow (ESI 3), and green (ESI 4 and 5). Horizontal dotted line represents RR = 1. Vertical dotted lines represent 5th percentile of temperature (blue = -3.9 °C) and 95th percentile of temperature (red = 23.3 °C).

reach statistical significance (Figure 3, Table 2). At extreme temperatures, confidence intervals widened due to the small number of extremely hot or cold days in the dataset, limiting statistical significance. Similarly, for extremes of acuity (ESI 1 and ESI 4 & 5), statistical significance may have been constrained by smaller sample sizes. DISCUSSION Our objective in this study was to analyze the relationship between temperature and ED arrivals across strata of patient acuity in a large, urban, academic medical center. To the best of our knowledge, the few studies examining the relationship between temperature and ED acuity have relied on predictive models, without specifically quantifying this relationship while Volume 27, Supplement: November 2026

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Impact of Daily Maximum Temperature on ED Arrivals and Acuity Levels

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Table 1. Summary characteristics of variables used in the analysis, including the percentage of days with data for each variable (eg, only 6.3 % of days had snowfall data). Median and range are reported for continuous variables. Variable

Category

Units

Proportion of Dates

Date

index

Arrival count

outcome

arrivals per day

ESI level

ordinal

rank of ESI, (ie, 1-5)

100%

Day of week

calendar

categorical day of the week (eg, Monday)

100%

Day of holiday

calendar

holiday, yes or no

Day before holiday

calendar

day following a holiday, yes or no

Day after holiday

calendar

day following a holiday, yes or no

Precipitation

weather

mm of precipitation, daily total

35.7% 0.33 [ 0.01 - 3.40]

Snow

weather

mm of snow, daily total

6.3% 2.3 [0.1 - 22.1]

Wind speed

weather

average wind speed, meters/second

100% 10.8 [ 1.7 - 36.7]

Temperature max

weather

maximum daily wet-bulb temperature, ℃

100% 10.8 [-13.9 - 27.2]

ESI, Emergency Severity Index; mm, millimeter.

[1/1/2010 - 12/30/2019] 100% 152 [61 - 228]

and low temperatures are associated with increased mortality, with greater effects observed at higher temperatures. Here, however, we found decreased risk of ED arrivals at lower temperatures, even in sub-zero winter weather.

scope of this study. Future studies in diverse geographic regions, incorporating more detailed stratification of presenting etiologies, are warranted to address these limitations and enhance the power and generalizability of these findings. Understanding the impact of extreme heat on ED arrivals and healthcare use is crucial for development of data-informed climate change adaptation and preparedness strategies. This study and future research examining how heat affects ED acuity may help administrators optimize staffing and resource allocation leading up to or during heat waves. Further stratification by clinical condition could provide valuable insight to inform targeted patient outreach and education programs, enabling healthcare systems to support patients in remaining safe during extreme weather events.

LIMITATIONS While the large sample size and extended study period are important strengths of this analysis, some limitations must be considered. First, the data are from a single urban center located in a geographical region with a limited number of extreme heat days. This limits the generalizability of our findings to other geographical regions with different characteristics, including differences in physiologic, cultural, and infrastructure-related resilience to the effects of temperature extremes. Second, as noted above, the small number of days at the extreme ends of the temperature spectrum limited the power of our analysis in detecting statistically significant trends at the extremes, particularly for extreme heat, which is of growing interest in the setting of climate change. Additionally, the 95th percentile wet-bulb temperature in coastal Massachusetts observed during the study period likely poses less heat stress compared to temperatures at other locations in the United States, such as the Southern and Southwestern states. This may have further limited the observed impact of the hottest days on acuity of ED arrival, which would be expected to be more pronounced in regions with greater heat extremes. Finally, ED arrivals were not stratified by traumatic vs non-traumatic etiologies or by specific diagnosis, which likely respond differently to temperature variations. Here, we focused on the acuity level upon arrival to the ED, while differences in management, length of stay, or admission rates were beyond the Western Journal of Emergency Medicine

CONCLUSION In this retrospective study focusing on a temperate region, we found that extremes of temperature, particularly heat, appear to affect ED arrivals differently across different acuity levels. Hotter weather was associated with increased relative risk of moderate-to-high acuity ED arrivals, but relative risks of very high and low acuity arrivals were less associated with extremes of temperature. A non-statistically significant numerical increase in ESI 1 presentations, and a non-statistically significant numerical decrease in ESI 4 and ESI 5 presentations were noted on the hottest days. This study did not directly evaluate operational costs, staffing impacts, or patient outcomes associated with these changes. To understand the potential impact of extreme heat on ED operations nationwide and inform data-driven climate change preparedness strategies, additional research is necessary on both arrival 34

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Table 2. Relative risk of emergency department arrivals and the corresponding 95% confidence interval for each Emergency Severity Index category at lag 0 associated with various temperature points. Blue boxes indicate a statistically significant relative risk < 1, while orqange boxes indicate a statistically significant relative risk > 1. RR [CI] Total Arrivals

RR [CI] ESI 1

RR [CI] ESI 2

RR [CI] ESI 3

RR [CI] ESI 4 & 5

-13.89

Exposure temp

0.94 [0.88 - 1.01]

0.95 [0.73 - 1.23]

0.96 [0.84 - 1.09]

0.93 [0.84 - 1.02]

1.00 [0.77 - 1.31]

-11.73

0.94 [0.90 - 0.98]

0.95 [0.82 - 1.11]

0.94 [0.87 - 1.01]

0.92 [0.87 - 0.98]

1.00 [0.86 - 1.17]

-9.56

0.94 [0.91 - 0.96]

0.96 [0.87 - 1.05]

0.93 [0.89 - 0.98]

0.93 [0.90 - 0.96]

1.00 [0.91 - 1.10]

-7.40

0.94 [0.92 - 0.96]

0.96 [0.89 - 1.04]

0.93 [0.90 - 0.97]

0.93 [0.91 - 0.96]

1.00 [0.93 - 1.08]

-5.23

0.95 [0.93 - 0.97]

0.96 [0.90 - 1.03]

0.94 [0.91 - 0.97]

0.94 [0.92 - 0.97]

1.00 [0.93 - 1.07]

-3.07

0.96 [0.94 - 0.97]

0.96 [0.91 - 1.02]

0.95 [0.93 - 0.98]

0.95 [0.93 - 0.97]

0.99 [0.94 - 1.05]

-0.91

0.97 [0.95 - 0.98]

0.96 [0.91 - 1.02]

0.96 [0.94 - 0.99]

0.96 [0.95 - 0.98]

0.99 [0.94 - 1.04]

1.26

0.97 [0.96 - 0.99]

0.97 [0.92 - 1.01]

0.97 [0.95 - 0.99]

0.97 [0.96 - 0.99]

0.99 [0.95 - 1.04]

3.42

0.98 [0.97 - 0.99]

0.97 [0.93 - 1.01]

0.98 [0.96 – 0.99]

0.98 [0.96 - 0.99]

0.99 [0.95 - 1.03]

5.58

0.98 [0.98 - 0.99]

0.98 [0.95 - 1.01]

0.99 [0.97 - 1.00]

0.98 [0.97 – 0.99]

0.99 [0.96 - 1.02]

7.75

0.99 [0.98 – 0.99]

0.98 [0.96 - 1.00]

0.99 [0.98 - 1.00]

0.99 [0.98 – 0.99]

0.99 [0.97 - 1.01]

9.91

0.99 [0.99 – 0.99]

0.99 [0.98 - 1.00]

0.99 [0.99 – 0.99]

1.00 [0.99 - 1.00]

12.08

1.01 [1.01 - 1.01]

1.00 [1.00 - 1.00]

1.01 [1.01 - 1.01]

1.00 [1.00 - 1.00]

14.24

1.01 [1.01 - 1.01]

1.01 [1.01 - 1.03]

1.01 [1.01 - 1.01]

1.01 [1.00 - 1.02]

16.40

1.02 [1.01 - 1.02]

1.02 [1.01 - 1.05]

1.02 [1.01 - 1.03]

1.01 [1.01 - 1.02]

1.01 [0.99 - 1.04]

18.57

1.03 [1.02 - 1.04]

1.04 [1.00 - 1.08]

1.03 [1.01 - 1.05]

1.02 [1.01 - 1.04]

1.02 [0.99 - 1.06]

20.73

1.04 [1.02 - 1.05]

1.05 [0.99 - 1.11]

1.04 [1.02 - 1.07]

1.04 [1.02 - 1.06]

1.03 [0.98 - 1.08]

22.89

1.04 [1.03 - 1.06]

1.04 [0.98 - 1.10]

1.04 [1.01 - 1.07]

1.05 [1.03 - 1.07]

1.03 [0.97 - 1.09]

25.06

1.04 [1.02 - 1.06]

1.02 [0.94 - 1.11]

1.06 [1.02 - 1.10]

1.04 [1.01 - 1.07]

0.98 [0.91 - 1.06]

27.22 1.02 [0.95 - 1.10] 1.06 [0.79 - 1.42] 1.16 [1.01 - 1.32] 0.97 [0.87 - 1.08] 0.83 [0.63 - 1.10] Note: The relative risk of ED arrivals stratified by acuity for lag 0, lag 1, lag 2, lag 3, and a lag aggregate can be found in the Appendix. ESI, Emergency Severity Index; CI, confidence interval; RR, relative risk.

volumes and on these operationally relevant endpoints in climatically diverse geographic regions that may experience more frequent temperature extremes, ideally incorporating more detailed stratification of presenting etiologies.

REFERENCES 1. Rohde R. Global Temperature Report for 2024. Berkeley Earth. 2025 Jan. Available at: https://berkeleyearth.org/global-temperature-reportfor-2024/. Accessed April 24, 2025. 2. Intergovernmental Panel on Climate Change (IPCC). Climate Change 2023: Synthesis Report. Contribution of Working Groups I, II, and III to the Sixth Assessment Report of the Intergovernmental

Address for Correspondence: Catharina Giudice, MD, Department of Emergency Medicine, Beth Israel Deaconess Medical Center; Harvard Chan Center for Climate, Health and the Global Environment, Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts. 1 Deaconess Road, Boston, MA 02215 Email: cgiudice@bidmc.harvard.edu.

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Copyright: © 2025 Giudice et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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narrative systematic literature review. BMJ Open. 2016;6(2):e010399. 7. Nyadanu SD, Dunne J, Tessema GA, et al. Maternal exposure to

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Original Research

Emergency Department Management of Acute Heatstroke: A Retrospective Analysis from Phoenix, Arizona Jeffrey R. Stowell, MD*†‡ Paul Pugsley, MD*†‡ Megan McElhinny, MD*†‡ Geoffrey Comp, DO*†‡ Jacquelyn Pearlmutter, DO*‡ Murtaza Akhter, MD*†‡§|| David Sklar, MD*†‡#

*Creighton University School of Medicine, Phoenix, Department of Emergency Medicine, Phoenix, Arizona †University of Arizona College of Medicine, Phoenix, Department of Emergency Medicine, Phoenix, Arizona ‡Valleywise Health, Department of Emergency Medicine, Phoenix, Arizona §Penn State Health Milton S. Hershey Medical Center, Department of Emergency Medicine, Hershey, Pennsylvania ||HCA Healthcare, Department of Emergency Medicine, Miami, Florida #Arizona State University, School of Medicine and Advanced Medical Engineering, Tempe, Arizona

Section Editor: Shahram Lotfipour, MD, MPH Submission history: Submitted January 1, 2025; Revision received June 8, 2025; Accepted June 8, 2025 Electronically published September 25, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI: 10.5811/westjem.42051

Introduction: The global incidence and severity of severe heat illness is on the rise. The increasing number of summer heatwaves in Phoenix, Arizona, gave us a distinctive opportunity to better understand the impact on the clinical presentation and management of acute heatstroke. Our primary objective in this study was to describe the prehospital and emergency department (ED) clinical presentation, treatment, and outcomes of patients with acute heatstroke at a single hospital system during the summers of 2021 and 2022 in Phoenix. Methods: This was a descriptive, retrospective observational study of heatstroke-associated adult ED presentations occurring from June 1 – August 31, 2021 and June 1 – August 31, 2022, to a single hospital system in Maricopa County. Results: We identified 60 ED heatstroke encounters. The median environmental daily maximum (Tmax) and minimum (Tmin) were 106.0° Fahrenheit (interquartile range [IQR]) 102.0 - 109.0°F) and 84.0°F (IQR 79.0 - 88.0°F), respectively. The patients were commonly male (42, 70.0%, 95% CI 56.8 - 81.2%), White (26, 43.3%, 95% CI 30.6 - 56.8%), middle-aged (mean 52.7 years, 95% CI 48.4 - 56.9), Medicaid-insured (37, 61.7%, 95% CI 48.2 - 73.9%), and presenting via emergency medical services (60, 100%). Patients were commonly of high acuity (median Emergency Severity Index 1, IQR 1.0 - 2.0), and intubated (45, 75.0%, 95% CI 62.1-85.3%). Forty-seven (78.3%, 95% CI 65.8 - 87.9%) patients were found unresponsive outside with associated substance use (methamphetamines 22, 46.8%, 95% CI 32.1 61.9%; and fentanyl 14, 29.8%, 95% CI 17.3 - 44.9%). The average patient Tmax at ED presentation was 41.9°C (IQR 41.1 - 42.2). Forty-one patients (68.3%, 95% CI 55.0 - 79.7%) survived to hospital discharge or transfer, of whom 32 (82.1%, 95% CI 66.5 - 92.5%) were neurologically intact. Conclusion: During the summers of 2021 and 2022, a significant number of heatstroke presentations were treated in a single healthcare system in Maricopa County, Arizona. A substantial number were successfully treated with cold water immersion and discharged neurologically intact. In this urban population, extreme weather exposure and associated substance use appeared to play significant roles. [West J Emerg Med. 2025;27(6.1)37–46.]

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ED Management of Heatstroke

Stowell et al.

INTRODUCTION Climate change has contributed to an increase in global heatwave frequency and severity, which is predicted to continue for decades to come.1-3 As a result, the global incidence of heat illness is on the rise.3 Severe heat-associated illness, such as heatstroke, is a significant cause of morbidity worldwide. Heatstroke mortality rates approach 50% in its most severe forms and disproportionately impacts the elderly and very young, as well as individuals with comorbidities, economic stress, and social disadvantages.2,4-9 Climate change modeling predicts the number of excess deaths due to heat illness to increase 233% by midcentury.10 In Phoenix, Arizona, the Maricopa County Department of Public Health (MCDPH) recorded an increase in heatstroke deaths from 61 in 2014 to 425 in 2022.11,12 In 2021 and 2022, the city of Phoenix experienced its 10th and 12th hottest years in recorded history, respectively.13 During the 2021 and 2022 summers, record maximum temperatures reached as high as 118°F, with 22 days of temperatures ≥ 110°F (43.3°C) in each of those years.13 Our primary objective in this study was to describe the prehospital and emergency department (ED) presentation of severe heat-associated illness, including the causes, clinical features, therapeutic approaches, and outcomes at a single hospital system during the summers of 2021 and 2022. A description of these patients will help expand our current understanding of the presentation and management of heat-associated illness, assist in developing additional preventative and therapeutic opportunities, and better prepare emergency physicians and public health professionals for the future impact of extreme heat events.

Population Health Research Capsule What do we already know about this issue? The incidence and severity of global heatwaves and heat illness are rising. Heatstroke is a significant cause of morbidity with mortality rates approaching 50%. What was the research question? We sought to describe the presentation of heatstroke, including the causes, clinical features, therapeutic approaches, and outcomes. What was the major finding of the study? 68.3% (CI 55.0 - 79.7%) of heatstroke victims survived to hospital discharge, with 82.1% (CI 66.5 - 92.5%) neurologically intact. How does this improve population health? A description of how severe heat-associated illness presents to the ED helps expand our understanding of its presentation and management and develop preventative measures.

Annually during 2006 - 2016, the county had a mean of 140 days with daily maximum temperatures of ≥ 90 °F (32 °C) and a mean of 57 days with daily maximum temperatures ≥ 105 °F (40.5 °C).16 The Arizona Emergency Information Network defines “extreme heat” as at least 2-3 days with temperatures above 90 °F.17 In 2022, 424 heat-associated deaths were identified in Maricopa County, 58% of which occurred in July12; this was a 25% increase over 2021. A 2005 heat event in Maricopa County prompted the formation of the City of Phoenix Heat Relief Network.11 Cooling stations in Maricopa County were open and available to the public throughout the study time frame.18

METHODS Study Design We conducted a retrospective, observational study of heatassociated, individual adult ED visits over two consecutive summers between June 1–August 31, 2021 and June 1–August 31, 2022, to a single hospital system located in the Phoenix, Arizona, metropolitan area of Maricopa County. The study protocol was approved by the local institutional review board. No author conflicts of interest were identified prior to data collection. Study Population and Setting The study was conducted across three EDs in a large, urban, multisite, safety-net healthcare system. The annual combined ED census of the hospital system is ≈ 107,000 total patient encounters. The ED uses a variety of approaches to patient cooling including non-immersion cooling (eg, the application of cold towels, ice packs, fans, etc) and cold water immersion.14 The selection and deployment of cooling therapy is at the discretion of the treating emergency medicine physician. Located in the Sonoran Desert, Maricopa County has a population of ≈ 4.551 million people living in a catchment area of 9,224 square miles.15 The arid climate is traditionally hottest from May – October with relatively low humidity.11 Western Journal of Emergency Medicine

Study Protocol Adult patients ≥ 18 years of age who presented to the ED with heatstroke from June 1 – August 31, 2021, and June 1 – August 31, 2022, were included in the study. We defined heatstroke as the combination of a temperature of ≥ 40.0 °C and central nervous system dysfunction (eg, altered level of consciousness) during the prehospital or ED course, which was either attributable to or associated with environmental heat exposure.9,19 Heatstroke was further defined as “classic” if due to the inability to avoid or physiologically adjust to heat exposure (eg, elderly or chronically ill persons), or 38

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Study Analysis This study was designed as a descriptive analysis of ED heatstroke presentations that occurred in the summers of 2021 and 2022. We identified and described presentations of acute heatstroke, including patient demographics, diagnostics, and therapeutic cooling interventions. Confidence intervals for frequencies were calculated using the Aggresti-Couli method (Wald approximation with correction). We made group comparisons using means and the Student t-test for normally distributed data, and medians and Mann-Whitney U testing for non-normally distributed data. Additionally, we described Phoenix, Arizona, meteorologic data using mean, median, interquartile range, and CIs, where appropriate. A graphical representation of heatstroke presentations geolocated to heat relief resources was created using Google Maps (Google LLC, Mountain View, CA). If study participant data were incomplete or unavailable, those encounters were noted in the results as “unknown.” We performed statistical analysis using Microsoft Excel (Microsoft Corp, Redmond, WA) and R v4.0.5 (The R Foundation for Statistical Computing, Vienna, Austria).

“exertional” if associated with strenuous physical activity (eg, outdoor labor or activity).19 Encounters that could not be defined as either were classified as “unclassified.” We defined ED cooling as the time from the first ED core temperature recorded to the first temperature of ≤ 39 °C. We excluded from analysis pediatric patients < 18 years of age at the time of ED presentation, and those with presentations that could not be attributed to heatstroke after chart review. We collected participant demographics, prehospital, ED, and hospitalization course information through chart extraction. We used multiple chart review and retrospective study best practices, including the Strengthening the Reporting of Observational Studies in Epidemiology guidelines, during study design, which included the creation of a standardized abstraction codebook20-23 (Supplemental Table 1). Three of the study investigators—experienced emergeny medicine physicians— extracted study data from the electronic health record (Epic Systems Corporation, Verona, WI). Prior to data collection they were trained per the study protocol, with ongoing education and review as needed. Training included an in-person guided review session with each extractor and supervised extraction of initial data. They used the codebook when extracting data from ED encounters that met study inclusion criteria. Discrepancy or disagreement was adjudicated through cross-abstractor validation.

RESULTS From June 1 – August 31, 2021, and June 1 – August 31, 2022, 45,428 total ED encounters occurred at the study site. Of these, we excluded 6,695 patients < 18 years of age at the time of ED presentation. Of the adult encounters, 32,468 were excluded due to a temperature < 40.0 °C. Of those patients with a temperature of ≥ 40.0 °C at the time of ED presentation, 6,199 were excluded because the presentation was unrelated to environmental heat exposure (eg, infection). Of the remaining encounters, we excluded an additional six patient encounters that were determined not to meet the definition of heatstroke as no central nervous system dysfunction was identified during either the prehospital or ED course (eg, heat exhaustion). A total of 60 adult ED encounters from June 1 – August 31, 2021, and June 1 – August 31, 2022, were determined to be due to acute heatstroke (Figure 1). Heatstroke patients were most commonly male (42, 70.0%, 95% CI 56.8 - 81.2%), White (26, 43.3%, 95% CI 30.6 - 56.8%), middle-aged (mean 52.7 years, 95% CI 48.4 56.9%), Medicaid-insured (37, 61.7%, 95% CI 48.2 - 73.9%), presenting via EMS (60, 100%), of high acuity (median Emergency Severity Index [ESI] – 1, IQR 1.0 - 2.0), having associated substance use (32, 53.3%, 95% CI 40.0 - 66.3%), and being homeless (22, 36.7%, 95% CI 24.6 - 50.1%). During the study period, the general ED population was 49.6% male, 78.4% White, 44.9% Medicaid-insured, and arrived via EMS in 22.8% of encounters. In the study population, 26 (43.3%, 95% CI 30.6 - 56.8%), and 16 (26.7%, 95% CI 16.1 - 39.7%) patients’ UDS results were positive for methamphetamines and fentanyl, respectively, while 14 (23.3%, 95% CI 13.4 36.0%) were positive for both. Twenty-three patients (38.3%, 95% CI 26.1 - 51.8%) received naloxone prior to ED arrival; 45 (75.0%, 95% CI 62.1 - 85.3%) were intubated, three (5.0%,

Study Measurements Demographics included patient age, gender, race, primary language, financial class, housing status, and primary heat illness diagnosis. The prehospital course included the following: pick-up location (ZIP code); initial non-core temperature; documentation of cardiopulmonary arrest; administration of naloxone and prehospital cooling; airway management; and narrative information regarding the circumstances of the heat exposure. The ED course included ED arrival method (private vehicle vs emergency medical services [EMS]), Emergency Severity Index (ESI) score, maximum core temperature (Tmax), Glasgow Coma Scale (GCS) score, ED intubation, urine drug screen (UDS) results, ethanol level, whether cardiopulmonary arrest occurred in the ED, ED cooling methods, and ED disposition (admit, discharge, death). Hospital course included admission level of care (intensive care unit [ICU], step-down, ward), hospital disposition (discharge or death), and neurologic status at the time of hospital disposition (per physician documentation, return to baseline neurologic status, new disabled, disposition needs, etc). Investigators also collected publicly available Maricopa County 2021 and 2022 meteorologic, heat surveillance, and heat relief resources. Meteorologic data from June 1 – August 31, 2021, and June 1 – August 31, 2022, included maximum and minimum daily environmental temperatures, and heat advisory dates.24,25 The type of heat relief resources including locations of cooling center was obtained from the Office of Heat Response and Mitigation.26 Volume 27, Supplement: November 2026

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Stowell et al. Table 1. Demographics of patients who suffered heatstroke during the summers of 2021 and 2022.

Demographics

Adult heatstroke ED encounters (N = 60) (%, 95% CI)

Gender Male

42 (70.0%, 56.8 - 81.2%)

Female

14 (23.3%, 13.4 - 36.0%)

Unknown

4 (6.7%, 1.8 - 16.2%)

Age Years (mean)

52.7 (48.4 - 56.9)

Race Hispanic, Latino/a, or Spanish

12 (20.0%, 10.8 - 32.3%)

White

26 (43.3%, 30.6 - 56.8%)

Black

9 (15.0%, 7.1 - 26.6%)

American Indian or Alaska Native

5 (8.3%, 2.8 - 18.4%)

Other Asian

1 (1.7%, 0.04 - 8.9%)

Unknown

7 (11.7%, 4.8 - 22.6%)

Type of Insurance

Figure 1. Total number of emergency department encounters and reasons for exclusion from heatstroke study. ED, emergency department

37 (61.7%, 48.2 - 73.9%)

Medicare (%)

9 (15.0%, 7.1 - 26.6%)

Self-pay (%)

4 (6.7%, 1.8 - 16.2%)

Commercial (%)

2 (3.3%, 0.4 - 11.5%)

Unknown

8 (13.3%, 5.9 - 24.6%)

Domicile

95% CI 1.0 - 13.9%) in the prehospital setting. Nineteen (31.7%, 95% CI 20.3 - 45.0%) of the heatstroke patients did not survive to hospital discharge, with 15 (25.0%, 95% CI 14.7- 37.9%) and four (6.7%, 95% CI 1.8 - 16.2%) dying in the ED and inpatient setting, respectively. Of 14 patients (23.3%, 95% CI 13.4 - 36.0%) who suffered prehospital cardiopulmonary arrest, none were successfully resuscitated in the ED and they contributed to all but one of the ED deaths. Of the 60 patients with heatstroke, 45 survived beyond the ED, with seven (11.7%, 95% CI 4.8 - 22.6%) discharged from the ED and 38 (63.3%, 95% CI 49.9 - 75.4%) admitted to the hospital. Of those admitted, 31 (81.6%, 95% CI 65.7 - 92.3%) were admitted to the ICU. A total of 41of the 60 patients (68.3%, 95% CI 55.0 - 79.7%) survived to hospital discharge or transfer. Of the 39 who were discharged, 32 (82.1%, 95% CI 66.5 - 92.5%) were neurologically intact at the time of discharge. Study participant demographics are in Table 1. The median patient, prehospital non-core Tmax was 41.1°C (IQR 40.6 - 42.0 °C); core Tmax at ED presentation was 41.9°C (IQR 41.1 - 42.2) and post-cooling minimum temperature (Tmin) was 37.0°C (IQR 35.9 - 37.7°C). Thirty-six (60.0%, 95% CI 46.5 - 72.4%) patients had Western Journal of Emergency Medicine

Medicaid (%)

Domiciled

23 (38.3%, 26.1 - 51.8%)

Undomiciled

22 (36.7%, 24.6 - 50.1%)

Unknown

15 (25.0%, 14.7 - 37.9%)

ED arrival method Ground emergency medical services (%)

60 (100%)

Emergency Severity Index (ESI) ESI (median)

1 (IQR 1.0 - 2.0)

ED, emergency department; IQR, interquartile range

documentation of EMS-initiated prehospital cooling interventions. Prehospital cooling techniques included the use of or combination of cold intravenous fluids (22 patients), placement of ice packs (16), placement of wet towels (3), cold blanket (1), and other “unspecified” cooling measures (11). The ED cooling techniques included cold water immersion in 38 (63.3%, 95% CI 49.9 - 75.4%), nonimmersion cooling (eg, cold towels, ice packs, fans, etc) in 13 (21.7%, 95% CI 12.1 - 34.2%), and no cooling in 9 (15.0%, 95% CI 7.1 - 26.6%) of the heatstroke patients. Patients treated with cold water immersion therapy demonstrated an overall higher acuity with higher median ESI (1.0 IQR 1.0-2.0 vs. 2.0 IQR 1.0 - 2.0), median Tmax (42.0°C, 40

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Stowell et al. 95% CI 41.3 - 42.3°C vs. 40.7°C, 95% CI 40.2 - 41.6°C), intubation rate (78.9%, 95% CI 62.7 - 90.5% vs 68.2%, 95% CI 45.1 - 86.1%), rate of prehospital cardiac arrest (15.8%, 95% CI 6.0 - 31.3% vs. 7.7%, 95% CI 0.2 - 36.0%), and lower median Glascow Come Scale (3 (IQR 3.0 - 6.0) vs. 11 (IQR 7.0-13.0)) as compared to non-immersion cooling. In patients where the duration of cooling was documented, the median temperature reduction, duration, and rate of cooling was 3.06°C (95% CI 2.4 - 3.6°C), 35.0 minutes (IQR 26.3 56.3), and 0.08°C per minute (95% CI 0.05 - 0.12 °C) for cold water immersion therapy (34, 89.5% immersion encounters with documentation), and 2.65°C (95% CI 2.18 - 3.10 °C), 60.5 minutes (IQR 37.5 - 87.3), and 0.04 °C per minute (95% CI 0.03-0.06°C) for non-immersion (12, 92.4%). Cold Water Immersion study participant demographics and outcomes presented in Table 2. The overall mortality rates were 28.9% (95% CI 15.4 45.9%) for cold water immersion cooling and 7.7% (95% CI 0.2 - 36.0%) for non-immersion cooling. The “no-cooling” patients demonstrated the highest overall prehospital acuity. Seven of the nine no-cooling patients presented to the ED in cardiopulmonary arrest, likely contributing to the decision to pursue immediate Advanced Cardiac Life Support (ACLS) measures rather than initiation of ED cooling. Only nine (15.0%, 95% CI 7.1 - 26.6%) of the heatstroke presentations were attributable to a “classic” cause of heat exposure. Forty-seven (78.3%, 95% CI 65.8 - 87.9%) patients were found down outside and were difficult to classify distinctively as either classic or exertional heatstroke. These encounters were classified as “unclassified” causes of heatstroke. Further, four (6.7%, 95% CI 1.8 - 16.2%) patients expired without sufficient clinical context to determine the cause of the heat exposure. The “classic” heatstroke encounters were 44.4% male (95% CI 13.7 - 78.8%), median 62.0 years old (IQR 56.0-72.0), 100% domiciled (95% CI 66.4 - 100.0%), 55.6% intubated (95% CI 21.2 - 86.3%), and 88.9% (95% CI 51.8-99.7%) survived to hospital discharge or transfer. Two (22.2%, 95% CI 2.8 - 60.0%) of these presentations had associated methamphetamine use. The “unclassified” heatstroke presentations were predominately male (36, 76.6%, 95% CI 62.0 - 87.7%), younger (49.8 years old, 95% CI 45.3 - 54.3), homeless (22, 46.8%, 95% CI 32.1 - 61.9%), and associated with substance use (methamphetamines 22, 46.8%, 95% CI 32.1 - 61.9%, and fentanyl 14, 29.8%, 95% CI 17.3 - 44.9%). A description of the 47 “unclassified” heatstroke presentations is available in Table 3. The median environmental daily Tmax and Tmin during the study window was 106.0°F (102.0 - 109.0 °F IQR) and 84.0°F (79.0 - 88.0°F IQR), respectively. Figure 2 demonstrates the daily heatstroke survivors, deaths, and environmental Tmax and Tmin. Thirty-one (51.7%, 95% CI 38.4 - 64.8%) of the heatstroke presentations occurred in July, including seven (36.8%, 95% CI 16.3 - 61.6%) of the total study population deaths. The median July Tmax and Tmin were 106.5 °F (95% CI 102.3 - 111.0 °F) and 85.0°F (95% CI Volume 27, Supplement: November 2026

Table 2. Demographics and outcomes of patients who underwent cold water immersion cooling therapy. Cold water immersion encounters (N = 38) (%, 95% CI)

Demographics Age (Years, Mean)

50.2 (45.1-55.4)

Emergency Severity Index (Median, Interquartile Range)

1 (IQR 1.0-2.0)

Glasgow Coma Scale (Median, Interquartile Range)

3 (IQR 3.0-6.0)

Prehospital cooling

24 (63.2%, 46.0-78.2%)

Prehospital cardiopulmonary arrest

6 (15.8%, 6.0-31.3%)

Emergency department maximum temperature (median Fahrenheit)

42.0°F (41.3-42.3°F)

Prehospital intubation

2 (5.3%, 0.6-17.7%)

Emergency department intubation

28 (73.7%, 56.9-86.6%)

Outcome Death

11 (28.9%, 15.4-45.9%)

Discharge neurologically intact

20 (52.6%, 35.8-69.0%)

Discharge with neurological deficit

6 (15.8%, 6.0-31.3%)

Unknown disposition

1 (2.6%, 0.06-13.8%)

IQR, interquartile range

80.3 - 89.0 °F), respectively. Heatstroke deaths represented 13.0% of all-cause ED deaths in July. In 2021 and 2022 there were 29 heat advisory dates. Nine (47.4%, 95% CI 24.5 71.1%) of the total heatstroke deaths occurred during heat advisory dates. Heatstroke patients presented from 20 unique ZIP codes. Of these, 18 are in Phoenix and one each in the geographically adjacent cities of Glendale and Peoria. There were 23 and 31 publicly available cooling centers in the patient presentation ZIP codes in 2021 and 2022, respectively. The prehospital patient location and geographically available cooling resources are described by ZIP code in Figure 3. DISCUSSION As a result of increasing environmental heat and exposure, the incidence and severity of heat illness and heatstroke are on the rise.12,27 In this study, a total of 60 presentations of heatstroke were identified at a single center from June 1–August 31, 2021, and June 1–August 31, 2022, in Phoenix, Arizona, with as many as four acute presentations and two deaths in a single day. In this 41

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Table 3. Characteristics of patients with “unclassified” heat stroke.

Demographics

"Unclassified" heatstroke encounters (N = 47) (%, 95% CI)

Gender Male

36 (76.6%, 62.0 - 87.7%)

Female

8 (17.0%, 7.6- 30.8%)

Unknown

3 (6.4%, 1.3 - 17.5%)

Age (Mean, Years)

58.3 (50.9 - 65.7)

Housing Domiciled

12 (25.5%, 13.9 - 40.3%)

Homeless

22 (46.8%, 32.1 - 61.9%)

Unknown

13 (27.7%, 15.6 - 42.6%)

Temperature maximum (Median, Fahrenheit)

42.0°F (41.3 - 42.3)

Emergency department intubation

34 (72.3%, 57.4 - 84.4%)

Drug screen Methamphetamine

22 (46.8%, 32.1 - 61.9%)

Fentanyl

14 (29.8%, 17.3 - 44.9%)

Alcohol

4 (8.5%, 2.4 - 20.4%)

"Other"

16 (34.0%, 20.9 - 49.3%)

Negative

2 (4.3%, 0.52 - 14.5%)

Not obtained

18 (38.3%, 24.5 - 53.6%)

Prehospital naloxone

20 (42.6%, 28.3 - 57.8%)

Figure 2. 2021 and 2022 heatstroke and heat-related death as compared to environmental temperatures.

Emergency department cooling method Cold water immersion

32 (68.1%, 52.9 - 80.9%)

Non-immersion cooling

9 (19.1%, 9.1 - 33.3%)

No cooling

6 (12.8%, 4.8 - 25.7%)

of heat illness in the study population was significant with 85.3% requiring airway management, a 63.3% hospital admission rate, 81.6% of whom were admitted to the ICU, and 63.3% underwent cold water immersion. However, a substantial portion of the patients (68.3%) were ultimately discharged or transferred, 82.1% of whom were neurologically intact at the time. As compared to prior literature, a significant portion of the heatstroke presentations in this study population did not adhere to the classical or exertional models.19 The “classic” heatstroke presentation commonly affects those with preexisting health or socioeconomic conditions that result in the inability to appropriately avoid heat exposure.19,28,29 Alternatively, in the “exertional” presentation, patients are typically younger and exerting themselves beyond their ability to sufficiently dissipate heat.19 In this study, only nine (15.0%) presentations were clearly attributable to a classic cause of heatstroke. Most of the study population (47, 78.3%) presented after being found unresponsive in an outdoor urban environment, directly exposed to extreme heat. In this group, substance use disorder and homelessness appeared to play a significant role in their heat exposure and resultant illness. As compared to the remainder of the study cohort,

Outcome Death

15 (31.9%, 19.1 - 47.1%)

Discharge neurologically intact

26 (55.3%, 40.1 - 69.8%)

Discharge with neurological deficit

5 (10.6%. 3.5 - 23.1%)

Unknown disposition

1 (2.1%, 0.05 - 11.3%)

population, heatstroke disproportionately impacted males (70.0%), persons experiencing homelessness (36.7%), and those with substance use disorder (53.3%). These results align with the 2022 MCDPH heat death report, which noted 424 heat-associated deaths, of which 81% of patients were male, 41.9% were experiencing homelessness, and 67% had associated substance use disorder.12 The acuity and severity Western Journal of Emergency Medicine

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designed to induce rapid heat dissipation; these include the application of cold IV fluids and ice packs, evaporative cooling with fans, and cold water immersion.1,19 In the study population, 60.0% of the patients had documentation of prehospital-initiated cooling interventions. In the ED, cooling either continued or was initiated in 85% of encounters, with most undergoing cold water immersion (63.3%). While the overall non-immersion mortality rate was lower, cold water immersion was more commonly used in patients with a higher acuity (ESI 1 vs 2), intubation rate (78.9% vs 68.2%), rate of prehospital cardiac arrest (15.8% vs 7.7%), and core temperatures (median Tmax 42.0°C vs 40.7°C), which likely contributed to the higher mortality in this group. Despite this, cold water immersion therapy demonstrated a faster cooling rate (0.08°C per minute vs 0.04°C per minute) and shorter duration (median 35.0 minutes vs 60.5 minutes), cooling patients nearly twice as quickly as non-immersion therapy.5,36,37 Prehospital and ED cold water immersion therapy is often difficult to implement due to limited space, resources, and training.14 This is further complicated in patients presenting in cardiopulmonary arrest. In this study population, no heatstroke patients who presented to the ED in cardiopulmonary arrest survived to hospital admission. Of these patients 77.8% received no cooling interventions, potentially due to the challenging integration of cardiopulmonary resuscitation (CPR) with cooling interventions. However, prior studies have demonstrated simultaneous cold water immersion and ACLS, including CPR and defibrillation, to be safe and effective.38 The development of prehospital and ED cold water immersion therapy strategies, including the necessary resource allocation and training, which take into account cardiopulmonary arrest and the need for ACLS management, can potentially expedite cooling and improve outcomes in heatstroke patients with prehospital cardiopulmonary arrest, although they are challenging to implement.38,39 While the association between extreme environmental temperatures and the incidence of heatstroke and death is clear, a further understanding of the most relevant and predictable local weather metrics may help guide prevention strategies.40,41 In this study population, 36.8% of the patient deaths occurred in July, marked by the highest daily Tmax and Tmin. Similarly, in 2022 the MCDPH reported 58% of all heat deaths occurred in July and 25.2% occurred on days with an excessive heat warning.12 Predictive weather modeling is specific to the local climate. Warning systems use a variety of weather and heat metrics, such as daily mean, minimum, or maximum temperature, or composite indices of temperature and humidity, such as the heat index, to guide heat illness prevention strategies.17,34 Prior studies have also shown that heat-induced clinical presentations may counterintuitively begin to occur at moderate temperatures, below traditional advisory triggers.8,40 Heat advisory warning metrics and triggers may be challenging to standardize for both research and public health initiatives but should be adapted to local climates.8,42

Figure 3. Heatstroke presentations and available cooling centers by Phoenix metropolitan-area ZIP code.

this novel group was largely male (76.6%), experiencing homelessness (46.8%), and associated with substance use (methamphetamines 46.8%, fentanyl 29.8%) in those who were tested, which potentially underestimates the absolute prevalence in this population. Prior literature has demonstrated an increased mortality in heat-exposed patients with concomitant substance use, particularly stimulants.30-34 Substance use likely contributes to the patient’s inability to appropriately avoid or dissipate heat, resulting in a heat-associated toxidrome, or heat poisoning. In the study population, the risk of heatstroke presentation and death was most specifically associated with methamphetamine and fentanyl use, potentially limiting the patient’s access to cooling resources, inhibiting the patient’s ability to respond to the normal biological heat-avoidance triggers, and prolonging heat exposure. The 2022 MCDPH statistics similarly identified the association of substance use in 67% of all heat deaths, including methamphetamines and fentanyl in 93% and 44.4% of patients, respectively.12 This novel trend poses unique challenges to the prevention and treatment of heat illness due to the combination of extreme weather exposure and substance use. In a 2014 study of Arizona cooling centers, the most frequent reasons for turning people away were safety concerns due to individual behaviors (56%) and intoxication (32%).35 The unique role that substance use plays in exacerbating heatstroke presentations in Phoenix, and likely beyond, cannot be underestimated and is deserving of further study to identify additional heat exposure prevention strategies in this population. The treatment of heat illness in the prehospital and ED settings is logistically challenging. Cooling strategies are Volume 27, Supplement: November 2026

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Stowell et al. to underestimating certain study findings. Similarly, drug use or intoxication was defined by a positive urinary drug screen alone, but clinical features of intoxication could be consistently obtained through chart review. Finally, the sample size was too small to be able to control for potential confounders; however, to our knowledge, this is the largest dataset of ED heatstroke patients reported. Future prospective and comprehensive studies in disparate climates and populations are warranted to better understand environmental and heat illness in this and dissimilar populations.

A substantial portion of the study population was found to be undomiciled in an urban environment at the time of presentation. Similarly, Maricopa County heat death patients in 2022 were predominantly from outdoor and urban exposures (80%) and experiencing homelessness (41.9%).12 Prior literature has identified the highest heat mortality rates (0.3 per 100,000 population) in urban and metropolitan settings.8,12 Urban areas create “heat islands” due to the increased structural and impervious surface density, resulting in hotter daytime temperatures and limiting heat dissipation at night.43 The distribution and delivery of heat illness treatment and prevention resources to an urban and unhoused population can be challenging.32,44,45 “Heat vulnerability” maps, focused on urban areas and heat islands, may help predict areas at high risk for heat illness presentations, and guide the deployment of public health cooling resources.46 In this study population, the incidence and acuity of heatstroke presentation to a single urban system were significant and consistent with 2022 MCDPH data, which demonstrated 424 heatstroke deaths, a 25% increase in heat illness-associated deaths from 2021.12 For comparison, there were 660 motor vehicle deaths in Maricopa County in 2022.47 However, with timely cooling interventions, a substantial portion of the study patients were successfully discharged neurologically intact. These results demonstrate and support the need for significant and ongoing resource allocation to heat illness prevention and treatment. Additional investigation of this novel heatstroke presentation, including the associated risk of extreme weather, substance use, and outdoor and urban setting exposures is needed. Strategies should address the challenge of connecting public health and cooling resources to this high-risk patient population. Furthermore, the partnership of prehospital, public health, and emergency care systems is needed to optimize the prevention, early detection, and rapid treatment of heat illness.

CONCLUSION In a single-center study of an urban population during the summers of 2021 and 2022, a significant number of heatstroke presentations and heat-related deaths were identified in Phoenix, Arizona. In this population, the extreme weather and association of substance use appeared to play a major role in precipitating heatstroke risk. However, a substantial portion of patients were successfully treated, often through cold water immersion, and discharged neurologically intact. Future studies evaluating the combined roles of public health, prehospital, and emergency care are necessary for the prevention and treatment of this environmentally mediated public health emergency.

Address for Correspondence: Jeffrey R. Stowell, MD, Valleywise Health, Department of Emergency Medicine, 2601 E. Roosevelt St, Phoenix, AZ 85008. Email: Jeffrey_Stowell@dmgaz.org. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare.

LIMITATIONS During the development and implementation of this study several potential limitations were identified. The study population presented via EMS transport and represented a specific geographical sample of the Phoenix heatstroke cohort for the catchment area of the hospital system. The generalizability of the study population may be limited in less arid or rural settings. While this may not fully describe the entirety of the Phoenix metropolitan area, we do believe it is representative of a significant and important cohort of heatstroke presentations and is consistent with concurrent local public health reports.12 Additionally, certain patient demographic characteristics could not be fully obtained through retrospective chart extraction at the time of study development and analysis, limiting the ability to describe a selection of study patients in this analysis fully. These patients were included in the analysis as “unknown” where appropriate but may have led Western Journal of Emergency Medicine

Copyright: © 2025 Stowell et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES 1. Sorensen C, Hess J. Treatment and Prevention of Heat-Related Illness. N Engl J Med. 2022;387(15):1404-1413. 2. Romanello M, McGushin A, Di Napoli C, et al. The 2021 report of the Lancet Countdown on health and climate change: code red for a healthy future. Lancet. 2021;398(10311):1619-1662 3. Diffenbaugh NS, Scherer M. Observational and model evidence of global emergence of permanent, unprecedented heat in the 20(th) and 21(st) centuries. Clim Change. 2011;107(3-4):615-624. 4. Rublee C, Dresser C, Giudice C, et al. Evidence-Based Heatstroke

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ED Management of Heatstroke

Stowell et al. Management in the Emergency Department. West J Emerg Med.

20. Cuschieri S. The STROBE guidelines. Saudi J Anaesth.

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6. Watts N, Amann M, Arnell N, et al. The 2020 report of The Lancet

22. Gilbert EH, Lowenstein SR, Koziol-McLain J, et al. Chart reviews in

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7. Vicedo-Cabrera AM, Scovronick N, Sera F, et al. The burden of

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change. Nat Clim Chang. 2021;11(6):492-500.

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8. Vaidyanathan A, Saha S, Vicedo-Cabrera AM, et al. Assessment

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9. Bouchama A, Knochel JP. Heat stroke. N Engl J Med.

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10. Khatana SAM, Eberly LA, Nathan AS, et al. Projected Change

26. City of Phoenix. Summer Heat Safety. Available at: https://www.

in the Burden of Excess Cardiovascular Deaths Associated With

phoenix.gov/heat/resources/heatsafety. Accessed Febuary 9, 2024.

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16. The United States Census Bureau. Maricopa County. Available

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hyperthermic runners: comparison of two field therapies. Am J Emerg

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43. Saverino KC, Routman E, Lookingbill TR, et al. Thermal inequity

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38. Feinstein B, Kelley J, Blackburn P, et al. Synchronized cardioversion

44. Morano LH, Watkins S. Evaluation of diagnostic codes in morbidity

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resources/crashdata/facts.html. Accessed April 21, 2024.

Volume 27, Supplement: November 2026

Letter To The Editor

“Predictive Factors and Nomogram for 30-Day Mortality in Heatstroke Patients: A Retrospective Cohort Study” Jeffrey R. Stowell, MD*†‡ Geoff Comp, DO*†‡ Paul Pugsley, MD*†‡ Megan McElhinny, MD*†‡ Murtaza Akhter, MD*†‡§||

*Creighton University School of Medicine, Phoenix, Department of Emergency Medicine, Phoenix, Arizona † University of Arizona College of Medicine, Phoenix, Department of Emergency Medicine, Phoenix, Arizona ‡ Valleywise Health, Department of Emergency Medicine, Phoenix, Arizona § Penn State Health Milton S. Hershey Medical Center, Department of Emergency Medicine, Hershey, Pennsylvania || HCA Healthcare, Department of Emergency Medicine, Miami, Florida

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted July 14, 2025; Revision received July 20, 2025; Accepted July 20, 2025 Electronically published November 26, 2025 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.48882

[West J Emerg Med. 2026;27(6.1)47–48.]

We would also ask for a further description of the cooling therapy used in this study. The study authors note that “the average cooling time was 3.13 hours.” Given that the average core temperature at admission in the study was 39.09 ℃ and the stated goal temperature for cooling cessation was 38.5 ℃, or approximately a 0.59 ℃ reduction, this results in an approximate average rate of cooling of 0.003 ℃ per minute. Comp et al noted that cooling rates can be as fast as 0.13 ℃ per minute with cold water immersion.4 Further, the study authors note that “the average time from onset to initiation of treatment was 8.29 hours.” We concur with their assessment of the importance of initiating heatstroke care within the “golden window” of the first 30 minutes post heat exposure.5 The study authors report “a lower risk of death when the core temperature at 30 minutes after admission was below 39.5 °C,” yet it is unclear how often this occurred in this study as the care was, on average, initiated many hours after exposure, and most often lasted over three hours once initiated. How do the study authors believe the delay in the initiation of treatment and the prolonged cooling duration may have impacted their findings? Was this considered when developing the risk predictions? Further clarification of the cooling treatment, including how many patients were treated within the “golden window,” and the outcomes among this group, we believe, would be helpful to better understand the study findings. Overall, we applaud the study authors for their work and agree that this contributes to our current understanding of heatstroke management, continuing to emphasize the importance of timely cooling therapy. We are optimistic that additional descriptions of the study participants and the therapeutic interventions will further strengthen this work.

Dear Editor: With the continued rise in global environmental temperatures, and the resultant increase in heatstroke deaths,1 we would like to recognize and highlight the importance of the article “Predictive Factors and Nomogram for 30-Day Mortality in Heatstroke Patients: A Retrospective Cohort Study,” from Li et al published in May 2025.2 We agree that the management of heatstroke continues to be of increasing importance, which the study authors further support with their findings. However, after reviewing their methods, we believe further study participant detail could enhance readers’ understanding and applicability of their findings. The study authors cite the Chinese Expert Consensus on the Diagnosis and Treatment of Heatstroke to support their study inclusion criteria, which defines heatstroke as “a core temperature of > 40 °C AND abnormalities of the central nervous system, including changes in mental status, convulsions or coma AND accompanied by life threatening multiple organ damage.”3 However, the reported study inclusion criteria require only one of the following heatstroke-associated features: central nervous system dysfunction; core body temperature exceeding 40 °C; or functional impairment of multiple organs. According to the study results, the mean core temperature at admission was 39.09 °C. We feel this necessitates further detail of how many of the patients included in the study met the entirety of the heatstroke diagnostic criteria set forth by Liu et al, and specifically how many were noted to be hyperthermic, > 40 °C, at any point during their illness. A further description of the study population, clarifying the number of patients who were hyperthermic at any point, including prehospital temperatures, would help readers better interpret the study cohort. Volume 26, No. 6: November 2025

Western Journal of Emergency Medicine

Re: “Predictive Factors and Nomogram for 30-Day Mortality in Heatstroke Patients” We appreciate your consideration of these questions and welcome any feedback. Thank you.

Stowell et al.

REFERENCES 1. Khatana SAM, Eberly LA, Nathan AS, et al. Projected change in the burden of excess cardiovascular deaths associated with extreme heat by midcentury (2036-2065) in the contiguous United States.

Address for Correspondence: Jeffrey Stowell, MD, Creighton University School of Medicine, Phoenix Department of Emergency Medicine, 2601 E Roosevelt St, Phoenix, AZ 85008. Email: jeffrey_stowell@DMGAZ.org

Circulation. 2023;148(20):1559-69. 2. Li A, Zhang Y, Zhang X, et al. Predictive factors and nomogram for 30-day mortality in heatstroke patients: a retrospective cohort study. West J Emerg Med. 2025;26(3):657-66.

3. Yangtai G, Xiaokun Q, Huiyu F, et al. Expert consensus on the diagnosis and treatment of clinically isolated syndrome in China. Chinese J Neurol. 2022;55(4):280-9. 4. Comp G, Pugsley P, Sklar D, et al. Heat stroke management updates: a description of the development of a novel in-emergency department cold-water immersion protocol and guide for

Western Journal of Emergency Medicine

implementation. Ann Emerg Med [Internet]. 2024;1-10. 5. Heled Y, Rav-Acha M, Shani Y, et al. The “golden hour” for heatstroke treatment. Mil Med. 2004;169(3):184-6.

Volume 27, Supplement: November 2026

Original Research

Effect of Ice Consistency and Sodium Chloride Additives on Cooling Speed and Final Temperature for Cold Water–Ice Immersion in Heat Stroke Andrew Goldmann, MD* Bryan Yavari, BS†‡ David Sklar, MD*†‡

*Creighton University School of Medicine, Emergency Medicine Residency, Phoenix, Arizona †Arizona State University, College of Health Solutions, Phoenix, Arizona ‡University of Arizona College of Medicine–Phoenix, Phoenix, Arizona

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted June 27, 2025; Revision received November 3, 2025; Accepted November 11, 2025 Electronically published February 22, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.48490

Introduction: Heat stroke can rapidly progress to end organ damage and death if not promptly treated. The diagnosis is characterized by core body temperature > 40.5 °C. In this study we evaluate how the form of ice (crushed vs cubed), the addition of sodium chloride, and the initial temperature of water together affect the rate of cooling for standardized cooling bath mixtures used to treat patients experiencing heat stroke. Methods: We prepared four cold water immersion mixtures using 12 quarts of ice and 12 quarts of water (11.36 liters) under different conditions: Test Case 1: Cubed ice with trauma bay tap water (~35 °C); Test Case 2: Crushed ice with cold tap water (~24 °C); Test Case 3: Crushed ice with cold tap water plus four pounds of rock salt; Test Case 4: Cubed ice with cold tap water, After each mixture was poured into a 40-quart bucket and mixed thoroughly, we recorded the temperature at 20-second intervals over a total duration of 300 seconds using a food-grade thermometer. Room temperature during the experiment was 25.0 °C. Results: After 100 seconds, water from the trauma bay with cubed ice reached 6.2 °C, while cold tap water with cubed ice cooled to a slightly lower temperature of 5.5 °C. Crushed ice in cold tap water reached an even lower temperature of 3.6 °C. The coldest mixture was made with crushed ice with salt, which rapidly reduced the water temperature to 2.2 °C. It took approximately 300 seconds for all test groups to approach equilibrium, with final temperatures of 2.4. °C for cubed ice in trauma bay water, 1.4 °C for cubed ice in cold tap water, 1.2 °C for crushed ice in cold tap water, and 0.2 °C for crushed ice with salt in cold tap water. Conclusion: A mixture of cold tap water, crushed ice, and sodium chloride achieved a lower equilibrium temperature and cooled more rapidly than mixtures lacking salt, using cubed ice, or prepared with warmer initial water temperature. These findings suggest that optimizing cold water immersion protocols with crushed ice, added salt, and the coolest available tap water may enhance cooling speed in simulated mixtures. Whether these differences translate into improved patient outcomes remains to be determined. [West J Emerg Med. 2026;27(6.1)49–53.]

INTRODUCTION Heat stroke is a medical emergency that will rapidly progress to irreversible end organ damage and death if not Volume 27, Supplement: November 2026

promptly treated. The diagnosis is characterized by core body temperature > 40.5 °C and altered mental status, often with hemodynamic collapse, and a severe inflammatory response;1 49

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Implications for Cold-Water Immersion in the Treatment of Heat Stroke mortality can exceed 50% within the first 28 days.2 With rising global temperatures, urbanization, and amphetamine epidemics the rates of heat stroke are steadily climbing. In Maricopa County, Arizona, for instance, heat-related deaths doubled between 2020 and 2023 and have increased by eight times over the previous 10 years.3 Given that 2024 was the hottest year recorded globally, optimizing the speed of cooling for heat stroke patients by quickly obtaining the lowest possible water bath temperature is a variable that merits attention.4 Once heat stroke is recognized, the core modality of treatment is rapid cooling as every minute with core body temperature sustained above 40 °C leads to increased mortality and morbidity.5 Expert recommendations target normothermia within 30 minutes from recognition of heat stroke symptoms.6 Cold water immersion is the most effective treatment, achieving cooling rates of 0.20 to 0.35 °C per minute.7 This method involves submerging the patient in a bath of ice and water. Although simple in concept, the logistics of implementing cold water immersion can be challenging. In an ideal scenario one can imagine a tub of ice and water premixed to a target water temperature ready for use at a moment’s notice. This setup may be available at major sporting events or military training centers where exertional heat stroke may be anticipated; however, it is not feasible in emergency departments (ED), emergency medical services vehicles, and other settings where heatstroke is less routine. In these settings it is necessary to create the optimal ice water mixture from scratch. A 2025 paper in the Annals of Emergency Medicine describes a comprehensive protocol for cold water immersion that uses a body bag filled with 44 quarts of ice and 22-44 quarts of room temperature water to create a slurry.8 From a practical standpoint, this general guideline will suffice for implementation of the protocol in the ED setting. However, there is limited research into key variables such as the initial temperatures of the water and ice , the optimal ice-to-water ratio, the impact of ice shape (crushed, shaved, or cubed), and whether additives like salt can enhance cooling efficiency. The optimal components and technique of creating a cold-water immersion mixture remain undetermined, especially when considering real-world resource constraints. When cold water immersion is performed the primary conduit for heat transfer from the patient is the water component, which has far greater surface area contact with the patient than the ice component. The purpose of adding ice is not to directly cool the patient but to cool the water, which in turn cools the patient. Since water rather than ice is the primary medium for heat transfer, there is an inevitable delay in cooling as the mixture reaches equilibrium. In this study we aimed to systematically evaluate key factors influencing the rapid creation of an effective ice-water mixture. Specifically, we examined the role of tap water temperature, ice temperature, ice shape, and the potential benefit of adding salt to the mixture. Western Journal of Emergency Medicine

Goldmann et al. Population Health Research Capsule What do we already know about this issue? Heat stroke has high morbidity and mortality and requires rapid cooling for best outcomes, which is most effectively achieved with ice water immersion protocols. What was the research question? Is there potentially a way to improve ice water immersion protocols by adjusting ice form, water temperature, and adding salt? What was the major finding of the study? Crushed ice with salt cooled water to 0.2 °C, 2.2 °C colder than unsalted mixtures with cubed ice, reaching equilibrium faster. How does this improve population health? Improvements to cold water immersion protocols may combat rising rates of heat-related deaths in vulnerable populations.

METHODS We identified several potential sources of water for cold water immersion therapy in our ED. These sources included faucets located in each of our three trauma bays, a handwashing station across from the trauma bay, and a bathroom down the hall from the trauma bay. Faucets were set to cold and allowed to run for two minutes, at which point the temperature of the water was measured and recorded. Significant discrepancies in temperature were noted between the trauma bay faucets and hallway or bathroom faucets. This observation guided the design of four cold water immersion mixtures. We tested four mixtures of tap water and ice, with one mixture also containing sodium chloride (salt): 1) cubed ice (store bought, -1.11 °C) mixed with cold tap water from the hallway sink; 2) crushed ice (from the hospital café, -1.11 °C) with cold tap water from the hallway sink; 3) crushed ice (from the hospital cafe, -1.11 °C) with cold tap water from the hallway sink and salt; and 4) cubed ice (from the trauma bay freezer, -14.22 °C) with tap water from trauma bay 1. Each experiment was conducted with 12 quarts of ice and 12 quarts of water (11.36 liters) with four pounds of rock salt added to the crushed ice in the salt experiment. For each scenario the sourced ice originated from tap water without significant saline concentration. 50

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Goldmann et al.

Implications for Cold-Water Immersion in the Treatment of Heat Stroke Table. Measurements of water temperature from faucets in our emergency department in a study designed to determine the quickest way to lower water temperature for treating heatstroke patients. Faucet temperature set to cold after 2 minutes of running water (°C)

Figure. Line chart depicts the change in water temperature of four ice-water mixtures using different ice forms, water sources, and the addition of salt. Temperature measurements are shown in degrees Celsius on a logarithmic axis. ED, emergency department.

35.00

Trauma bay 2

35.56

Trauma bay 3

35.00

Bathroom sink

23.89

Hallway sink

23.89

DISCUSSION Our experiments demonstrated that a mixture of crushed ice with salt and cold tap water can reach a lower equilibrium temperature and do so more quickly than variations of other mixtures commonly used for cold water immersion. Additionally, the water obtained from the trauma bay was warmer than expected and took longer to achieve an adequate equilibrium temperature for cold water immersion, which highlighted the importance of lower initial water temperature in cold-water immersion protocols. We did not study whether these differences would be impactful when cooling heat-stroke patients. However, it is logical and mathematically consistent to conclude that a colder cold-water immersion mixture would yield faster cooling rates in hyperthermic patients. For example, cooling during cold water immersion approximately follows Newton’s law of cooling: dT/dt = k(Tbody – Tbath). With a relatively small absolute change in Tbody the formula can be simplified to a linear relationship in which the rate of decline in core body temperature is proportional to the temperature gradient between the body and the water bath. Empirical data and reasonable derivations suggest k values between 0.005–0.013 minutes⁻¹.7,9,10 Using a representative k = 0.013 minutes⁻¹, reducing bath temperature from 2.4 °C to 0.2 °C would increase the gradient from 39.6 °C to 41.8 °C, and the predicted average cooling rate from 0.51°C/minutes to 0.54 °C/minutes, shortening cooling time by roughly 0.41 minutes for a 4 °C reduction in core temperature. These findings could have significant clinical implications and should guide additional investigation into the effectiveness of hyperthermic treatment protocols. While establishing ideal ice, water, and salt additive ratios would require high-fidelity modeling or clinical trials, several key generalizable principles can still be identified based on our experiments and fundamental physical properties. Mathematically, the transfer of heat by convection from water to ice is proportional to the amount of surface area of contact between the two mediums. Thus, heat transfer is substantially greater with crushed or shaved ice in comparison to larger ice cubes. This effect was reflected in our

At the start of each experiment we set a timer, and all components specified were poured into a 40-quart bucket. As the mixture was briefly agitated to ensure even distribution of components, we measured the initial temperature. Subsequently, the temperature of each mixture was measured at 20-second intervals for a total duration of 300 seconds (five minutes). We used a standard food-grade thermometer inserted at random locations to a depth of approximately two inches below the waterline. Data were recorded and graphed on a logarithmic axis for improved pattern visualization.

RESULTS Faucet water temperature varied significantly at different locations around the ED. The water source in the resuscitation/ trauma bay, where most heat stroke patients are treated, was found to be 35 °C (95 °F) on the cold setting even after running for two minutes. In contrast, nearby hallway and bathroom sinks ran at 24 °C (75 °F) (Table). Room temperature during the experiment was 25.0 °C. The data compiled from our experiments measuring the temperature of cooling mixtures (ice cubes in tap water, crushed ice in tap water, crushed ice with salt in tap water, and ice cubes in trauma bay water) revealed substantial differences in the rate of cooling and achieving depth of equilibrium temperature. After 100 seconds, water from the trauma bay with cubed ice was the warmest, reaching 6.2 °C. Tap water with cubed ice ended slightly cooler at 5.5 °C, while crushed ice in tap water reached a lower temperature of 3.6 °C. The coldest mixture was crushed ice with salt in tap water, which rapidly reduced the water temperature to 2.2 °C. By 300 seconds all test groups approached equilibrium with final temperatures of 2.4 °C for cubed ice in trauma bay water, 1.4 °C for cubed ice in tap water, 1.2 °C for crushed ice in tap water, and 0.2 °C for crushed ice with salt in tap water (Figure). Volume 27, Supplement: November 2026

Trauma bay 1

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Implications for Cold-Water Immersion in the Treatment of Heat Stroke experiments, with crushed ice producing a more rapid drop in water temperature than cubed ice. When possible crushed or shaved ice should be used in cold-water immersion protocols. Alternatively, if only ice cubes are available, physically breaking up the ice before use in a cold-water immersion mixture may improve cooling efficiency. It should again be emphasized that the fluid component of cold-water immersion therapy is the primary medium for heat exchange; therefore, it stands to reason that the starting water temperature may be one of the most critical factors for a successful cold-water immersion mixture. When implementing a cold- water immersion protocol the selection of water source should be determined with the temperature of the water in mind. Our measurements of water temperature across the ED revealed that trauma bay faucets, while conveniently located, provided unacceptably warm water and could cause delays in cooling if used as the water source for cold water immersion. Alternative sources of water proved much more effective. Any medical facility seeking to implement a cold-water immersion protocol should make note of where water will be sourced and measure water temperature to ensure that the faucet temperature is in line with the goals of cold water immersion. If cold faucet water is not readily available, storing several gallons of refrigerated water at approximately 4 °C may provide a practical solution. Future studies could investigate whether ice is even necessary when the initial water temperature is sufficiently low. Although not previously considered or studied for use in cold water immersion, the addition of salt to an ice water mixture can facilitate more rapid cooling. By disrupting intermolecular bonds in water, salt lowers the freezing point and accelerates the phase transition of ice from solid to liquid. This results in a lower latent heat of fusion and a decreased freezing point, offering two potential advantages for cold water immersion. First, converting solid ice to liquid increases surface area contact with the patient, enhancing convective cooling. Second, the liquid component of the mixture can reach lower temperatures without freezing, theoretically as low as −21.1 °C in a saturated salt solution. From our experimentation we found that the addition of salt to an ice water mixture did produce a more rapid and profound drop in temperature. Salt is lightweight, inexpensive, easy to transport, and in theory could increase the efficiency of cold water immersion. However, prior to adopting the use of salt in cold water immersion clinically it will be important to further investigate the effect of dissolved salt on electrical monitoring equipment and defibrillation. While pure water has low electrical conductivity and previous case studies and simulations suggest defibrillation is safe in submerged patients, salt dissociates into ions that significantly increase conductivity and could increase the risk of redirecting electrical conduction pathways.11

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LIMITATIONS While recording during our experiments it is likely that the temperature probe made intermittent contact with ice rather than the surrounding water mixture. This may have led to an artificially low reading of 0.1° C at 20 seconds for the crushed ice and tap water test case. A perfectly mixed icewater slurry in which temperature equilibrates more evenly would not have this problem, but in real-world testing a probe in contact with a solid ice particle may register an exceptionally low temperature. This discrepancy was not observed in the crushed ice with salt condition where the rapid dissolution of salt facilitates uniform cooling and prevents localized cold spots. Repeating our experiment in a controlled environment could help clarify outliers and provide statistical significance to the differences we observed. An additional limitation is the absence of clinical testing of our cooling mixtures on patients with heat stroke or volunteer subjects, which prevents direct assessment of their performance in humans. While it is reasonable to expect that colder cold-water immersion mixtures would cool hyperthermic patients more rapidly and prior studies have shown that water temperatures of 1-5 °C cool more effectively than 20-26 °C, differences in cooling rates within the 1-17. °C range have not yet been shown to be statistically significant.12 Future studies should evaluate the feasibility of implementing these recommendations in clinical settings and assess their impact on patient outcomes. Developing standardized guidelines based on these findings could improve the efficiency of heat stroke treatment protocols. CONCLUSION The results of this study support the adoption of standardized cold-water immersion protocols that incorporate ice shape considerations and optimal water selection, ensuring more consistent and potentially effective treatment for heat stroke patients. Our study highlights several key findings that could enhance the efficiency of cold water immersion for heat stroke treatment in the emergency care setting. We found that crushed ice cools water more rapidly than ice cubes, likely due to increased surface area, and that the addition of salt further accelerates the cooling process by lowering the freezing point of water. We identified important variability between faucet temperature in the ED and, therefore, advise that medical staff monitor faucet temperatures to ensure that the water source for cold water immersion is as cold as possible. While our results suggest meaningful improvements to current practices, further research is needed to assess the clinical significance and feasibility of incorporating salt into cold water immersion, especially regarding its impact on electrical safety and medical monitoring equipment. Implementing these findings could improve the speed and effectiveness of heat stroke management, ultimately reducing morbidity and mortality associated with severe hyperthermia.

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Implications for Cold-Water Immersion in the Treatment of Heat Stroke the world’s warmest year on record. 2025. Available at: https://www.

Address for Correspondence: Andrew Goldmann, MD, Arizona State University College of Health Solutions, Health North Building, 550 N 3rd Street, Phoenix, Arizona,85004, Mail code 9020. Email: agoldmann@outlook.com.

noaa.gov/news/2024-was-worlds-warmest-year-on-record. Accessed Accessed May 1, 2025. 5. Patel J, Boyer N, Mensah K, et al. Critical illness aspects of heatstroke: a hot topic. J Intensive Care Soc. 2023;24(2):206-14.

6. Barletta JF, Palmieri TL, Toomey SA, et al. Society of Critical Care Medicine guidelines for the treatment of heat stroke. Crit Care Med. 2025;53(2):e490-500. 7. Casa DJ, McDermott BP, Lee EC, et al. Cold water immersion: the gold standard for exertional heatstroke treatment. Exerc Sport Sci Rev. 2007;35(3):141-9.

Copyright: © 2026 Goldmann et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

8. Comp G, Pugsley P, Sklar D, et al. Heat stroke management updates: a description of the development of a novel in-emergency department cold-water immersion protocol and guide for implementation. Ann Emerg Med. 2025;85(1):43-52. 9. Yang Z, Davis JK, Casa DJ, et al. Optimizing cold water immersion for exercise-induced hyperthermia: a meta-analysis. Med Sci Sports

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1. Epstein Y, Yanovich R. Heatstroke. N Engl J Med. 2019;380(25):2449-59.

10. Proulx CI, Ducharme MB, Kenny GP. Effect of water temperature on

2. Argaud L, Ferry T, Le QH, et al. Short- and long-term outcomes of

cooling efficiency during hyperthermia in humans. J Appl Physiol.

heatstroke following the 2003 heat wave in Lyon, France. Arch Intern

2003;94(4):1317-23.

Med. 2007;167(20):2177-83.

11. Lyster T, Jorgenson D, Morgan C. The safe use of automated

3. Maricopa County, Department of Public Health, Division of

external defibrillators in a wet environment. Prehosp Emerg Care.

Epidemiology and Informatics. 2023 Heat Related Deaths Report.

2003;7(3):307-11.

2024. Available at: https://www.maricopa.gov/ArchiveCenter/ViewFile/

12. Douma MJ, Aves T, Allan KS, et al. First aid cooling techniques for

Item/5820. Accessed October 10, 2024.

heat stroke and exertional hyperthermia: a systematic review and

4. National Oceanic and Atmospheric Administration (NOAA). 2024 was

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meta-analysis. Resuscitation. 2020:148:173-90.x

Western Journal of Emergency Medicine

Original Research

12-Year Case Series of Patients with Heat Illness from an Urban Hospital System in the American Southwest Megan McElhinny, MD, MPH*†‡ Logan Garr, BS* Tristan Chen, BS† Brandon Garcia, MD† Bikash Bhattarai, BVSc, MVSc, PhD‡ Liliya Kraynov, MD, MCR*‡ Geoff Comp, DO*†‡

*Creighton University School of Medicine-Phoenix, Department of Emergency Medicine, Phoenix, Arizona † University of Arizona, College of Medicine-Phoenix, Department of Emergency Medicine, Phoenix, Arizona ‡ Valleywise Medical Center, Department of Emergency Medicine, Phoenix, Arizona

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted July 14, 2025; Revision received October 28, 2025; Accepted November 18, 2025 Electronically published February 3, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.49002

Objectives: Climate change has led to more frequent and intense heat events with dramatic increases in heat illness and heat-related deaths. We compared demographic characteristics such as age, sheltering status, and underlying health conditions that contribute to susceptibility to extreme heat. We described the clinical course of these patients, presenting over a 12-year span, who were diagnosed with heatrelated illness, to inform local risk stratification. Methods: We conducted retrospective chart abstraction of encounters between January 1, 2012– December 31, 2023, which included adults 18-89 years of age, presenting to a single hospital system’s emergency department (ED), with an International Classification of Diseases, 10th Revision, discharge diagnosis within the T67 heat-related diagnosis code family. We compared demographic characteristics to baseline ED presentations and summarized clinical characteristics in frequencies. Trends were described over time juxtaposed with temperature data. Results: The 141 patients with a heat illness diagnosis were older, with a mean age of 53, and were more likely to be male (81.6%), White (51.8%), or Native American (7.8%) as compared to adult (1889 years of age) all-comer ED presentations. Patients with a heat illness often carried co-occurring diagnoses of contact burns (38.3%) or rhabdomyolysis (25.5%). Common chronic comorbid conditions included cardiovascular disease (33.3%) and substance use disorder (22.0%). Antipsychotics (22.0%), laxatives (24.1%), and beta blockers (15.6%) were frequent home medications among heat-affected patients. Of the patients who were the most critically ill from heat illness, 35.5% required ED intubation and 95.7% were admitted, with 45.9% of those requiring intensive care. While most were discharged to self-care (59.3%), 26.7% required skilled nursing care at discharge. Conclusion: This review describes the characteristics and clinical course of patients diagnosed with heat illness over more than a decade of increasingly frequent and extreme heat in Phoenix, AZ. It provides a unique and sizeable cohort that can guide the surveillance and treatment of heat illness. We highlight clinical trends and gaps in clinical heat illness data to identify vulnerabilities and protective factors among our patients. [West J Emerg Med. 2026;27(6.1)54–60.]

INTRODUCTION Background Climate change has led to a surge in extreme heat events, with rising temperatures posing significant threats to public

Western Journal of Emergency Medicine

health.1 Phoenix, Arizona, stands at the forefront of this climatic challenge, experiencing an increasing frequency and intensity of extreme heat events.2 The Maricopa County Public Health Department recorded 645 heat-related

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12 Year Case Series of Patients Diagnosed with Heat Illness in the Southwest

deaths in 2023, nearly double the deaths recorded just two years prior.3 In 2023 Phoenix experienced 133 days with a temperature greater than 100 ˚F and 55 days greater than 110 ˚F.4 Seasonal highs are increasingly more extreme and prolonged, particularly in the southwest United States (US). California, Arizona, and Texas, with similar hot climates, represent only 23% of the US population but accounted for a disproportionate 37% of heat deaths between 2004–2018.5 Of US climate-related fatality rates in 2023, extreme heat events were the deadliest.6 Factors such as demographics and underlying health conditions may contribute to an increased susceptibility to the adverse effects of extreme heat.7 In 2023, unsheltered people experienced an estimated 500-fold increased risk of death from a heat-related cause,8 representing 45% of heat-related deaths.3 In Maricopa County 75% of heatrelated deaths occurred outdoors in 2023, and unsheltered people using alcohol or illicit substances experience disproportionate consequences of extreme heat.9 Of the 419 deaths in 2023, 65% were associated with substance use, and 62% occurred among those experiencing homelessness.3

Population Health Research Capsule What do we already know about this issue? Among US climate-related fatalities, extreme heat events were the deadliest in 2023, including 419 heat-related deaths in Maricopa County, Arizona. What was the research question? We described the clinical course of patients diagnosed with heat-related illness over 12 years at a safety-net hospital system. What was the major finding of the study? Patients were predominantly White (52%) males (82%) with a mean age of 53; 96% were admitted, and 27% were discharged to skilled nursing. How does this improve population health? These new clinical data, among a sizable cohort, highlight fundamental gaps in identifying and collecting data in affected populations and inform surveillance and risk stratification.

Importance The implications of extreme heat on healthcare are farreaching.3 The increasing incidence of heat-related disease imposes a growing and resource-intensive demand on clinicians and healthcare systems. Emergency medicine stands at the forefront of recognizing, resuscitating, and contributing to risk reduction of populations especially vulnerable to heat illness. An examination of patient characteristics and clinical course is vital to inform focused interventions and improve risk stratification.

based on a priori categories of high-risk medications (Appendix 3).7 Comparison ED all-comer data among adults (18-89 years of age) over the same study period were collected using Epic Slicer Dicer, a reporting and data visualization tool. Retrospective review included programmed extraction by data analysts for clinical characteristics and a two-reviewer manual chart review for clinical course outcomes. Outcomes data were collected by two trained reviewers (LG, BG) who reviewed encounters independently using a standard data collection form. Reviewers were trained using cohorts of 5-10 patients with review and comparison of variables in Research Electronic Data Capture, hosted at Valleywise Health, for consistency and agreement. Variations in abstraction were adjudicated by consensus among the reviewers and a senior author (MM). We modeled chart review methods using Strengthening the Reporting of Observational Studies in Epidemiology guidelines, including clear eligibility criteria, an a priori data-collection form, and trained reviewers with regular reassessment consistent with best practices in emergency medicine observational research and chart review.8-10 This study was reviewed by the local institutional review board (IRB) and deemed exempt.

Goals of This Investigation In this retrospective chart review we compiled a sizeable case series to describe the multifaceted nature of heat illnesses in Phoenix. Our aim in this study was to better understand how the demographics of this cohort vary from the general ED population, to observe the frequency of documented heatillness risk factors and to identfiy the resources required to care for these patients, informing clinical heat idenfication and treatment strategies. METHODS Study Design In this observational study we used a retrospective chart review to describe and analyze patient demographics, patient characteristics, and clinical course among those diagnosed with a heat-related illness. Programmed data extraction by our electronic health record (Epic Systems Incorporated, Verona, WI) data analysts was used to identify cases over the study period and to compile an a priori list of patient characteristic variables for each encounter. These data were cleaned by ordering and grouping by unique clinical identifier. Duplicate records were removed. We manually sorted home medications Volume 27, Supplement: November 2026

Setting and Selection of Participants We reviewed patient records from an urban, safetynet hospital system that included two adult emergency 55

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12 Year Case Series of Patients Diagnosed with Heat Illness in the Southwest departments (ED) and a burn center ED in Phoenix, AZ. Adults 18-89 year of age with an ED visit between January 1, 2012–December 31, 2023, were included. We included patients if they had any ED disposition diagnosis of heatrelated illness from the International Classification of Diseases 10th Revision (ICD-10) diagnosis class T67 family (Appendix A). Pediatric patients were excluded from this study. The IRB stipulated that patients >89 years of age be excluded as they were identifiable within our health system.

11) patients were represented at a greater rate in our study population as compared to the all-comer adult population, 20.2% (n = 141,176) and 3.6% (n = 25,293), respectively. In contrast, fewer Blacks were represented in our study population at 10.6% (n = 15) compared to 15.3% (n = 106,894). Hispanic or Latino ethnic groups were represented at a lower rate at 25.5% (n = 36) compared to 48.9% (n = 341,575). More common in our study sample were patients with a documented primary payor source of Medicaid at 57.4% (n = 81) vs 45.8% (n = 319,540), or commercial insurance at 16.3% (n = 23) vs 1.3% (n = 9,011). Fewer patients without insurance at 7.8% (n = 11) vs 27.8% (n = 193,999) were represented in our study population. Patients’ occupations and housing status were not reliably documented in either population. Documented housing status and occupation were absent in all charts electronically reviewed. Of the study population, 34.8% (n = 49) vs 16.3% (n =. 113,854) claimed 85008 as their home ZIP code, which includes our primary medical center. The second and third most common ZIP codes among the study population resided adjacent to our medical center, including 85007 at 7.1% (n = 10) vs 3.2% (n = 22,258) and 85006 at 5.0% (n = 7) vs 3.9% (n = 27,342), respectively. The next most represented ZIP codes were 85040 (5.0% [n = 7] vs 4.9% [n = 34,314]), which is not directly adjacent to the primary medical center, and 85018 (2.8% [n = 4] vs 1.6% [n = 11,322]), which is adjacent to a secondary medical center opened in 2019 (Table 1).

Outcomes Our primary objective was to describe the characteristics and clinical course of patients diagnosed with heat illness in the ED. Variable selection was based on literature citing risk factors for heat illness, including comorbid conditions, medications, and social demographics.7,13 A priori demographic characteristics included age, sex, race, ethnicity, ZIP code, and payor source, with employment status and housing status inadequately captured. Clinical characteristics extracted included comorbidities previously identified as risk factors (based on available diagnostic groupers in Appendix B), commonly co-occurring clinical diagnoses, and home medications known to predispose patients to heat illness.7,11 We also assessed return ED visits within 30, 60, and 90 days from the index visit. Manual, two-reviewer chart review assessed outcomes that were difficult to obtain with programmed extraction alone. These variables included ED length of stay (LOS), whether ED intubation was performed, ED disposition, admission level of care, admission LOS, admission disposition, and gross neurological status on discharge. Secondary outcomes included publicly available climate data from the National Weather Service, including maximum and minimum temperatures in the Phoenix area over the study period.14

Patient Clinical Characteristics A large segment of the study population was given a diagnosis code of contact burns (38.3%, n = 54) or rhabdomyolysis (25.5%, n = 36), but fewer received a diagnosis of altered mental status (5.7%, n = 8). Notably, our main adult ED remains a regional burn referral center. Frequency of comorbidities included cardiovascular disease (33.3%, n = 47), substance use disorder (22.0%, n = 31), respiratory disease (8.5%, n = 12), diabetes (8.5%, n = 13), and obesity (8.5%, n = 12). Typical blood pressure agents on patient home medication lists included beta blockers (15.6% n = 22) and calcium channel blockers (15.6% n = 22). Laxatives were a common medication among the study population (24.1%, n = 34). While we did not collect information on mental illness among our study population, antipsychotics (22.0%, n = 31) were common, as was lithium (11.3%, n = 16). Additionally, 7.8% (n = 11) of study patients had a benzodiazepine on their home medication list. The broad category of anticholinergics, including everything from breathing treatments (ipratropium) to allergy medication (diphenhydramine), was included in the home medications of 18 study participants (12.8%). Antihistamine medications were also prevalent at 17.0% (n = 24) (Table 2). This cohort represents a high-acuity group, likely those with the most severe forms of heat illness. Most patients dispositioned from the ED with a diagnosis of heat-related

Analysis We summarized demographics, clinical characteristics and clinical course using descriptive data, including frequencies and percentages. The number of patient visits with an ICD-10 heat-related diagnosis per year was represented visually over time, juxtaposed against daily temperature highs and lows.14 Given the nature of this descriptive analysis among a case series, no causal inference or other hypothesis testing analysis was appropriate. RESULTS Patient Demographic Characteristics Patients with an ED discharge diagnosis related to heat illness were older, with a mean age of 53 years (2384), compared to a mean age of 41 (18-89) among all ED presentations for adults aged 18-89. Among the studied patients, 115 (81.6%) were male compared to 50.1% (n=349,829) in the comparison population. White (51.8%, n = 73) and Native American (7.8%, n = Western Journal of Emergency Medicine

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Table 1. Patient demographics in a study of heat illness and heat-related deaths in Phoenix, Arizona. Heat-related diagnosis (N = 141)

Adult (18-89 years) ED encounters (N = 698,235)

Age (median [range])

Total

53 years (23-84)

41 years (18-89)

Male sex (% ([n])

81.6% (n = 115)

50.1% (n = 349,829)

White

51.8% (n = 73)

20.2% (n = 141,176)

Black

10.6% (n = 15)

15.3% (n = 106,894)

Hispanic

25.5% (n = 36)

48.9% (n = 341,575)

Native American

7.8% (n = 11)

3.6% (n = 25,293)

Asian

0.7% (n = 1)

1.4% (n = 9,671)

57.4% (n = 81)

45.8% (n = 319,540)

Medicare

11.3% (n = 16)

11.2% (n = 78,286)

Commercial Insurance

16.3% (n = 23)

1.3% (n = 9,011)

Uninsured

7.8% (n = 11)

27.8% (n =193,999)

Other

6.4% (n =. 9)

14.0% (n = 97,407)

85008

34.8% (n = 49)

16.3% (n = 113,854)

85007

7.1% (n = 10)

3.2% (n = 22,258)

85006

5.0% (n = 7)

3.9% (n = 27,342)

85040

5.0% (n = 7)

4.9% (n = 34,314)

2.8% (n = 4)

1.6 (n = 11,322)

Race/ethnicity (% [n])

Primary payor (%(n) Medicaid

Patient’s Primary ZIP Code

85018 ED, emergency department.

illness were admitted (95.7%, n = 135), with 4.3% (n = 6) discharged to home. No patients were deceased at ED disposition. While in the ED, 35.5% (n = 50) required intubation. Of those who were admitted to the hospital, 45.9% (n = 62) were admitted to the intensive care unit (ICU), 25.9% (n = 35) were admitted to progressive/step-down units and 28.1% (n = 38) to medical/surgical units. The median time to admission was 5 hours 19 minutes (1hour 22 minutes-22 hours 16 minutes) while the median hospital LOS was 2 days 18 hours 42 minutes (9 hours 54 minutes-63 days 18 hours 30 minutes). Of all patients alive at ED or hospital disposition, 94% (n = 125) were grossly neurologically intact at discharge based on the exam detailed at discharge. Patients were most commonly discharged from hospital admission to self-care (59.3%, n = 80) followed by skilled nursing facility (SNF) (26.7%, n = 36), inpatient behavioral health (5.7%, n = 8), and legal custody (2.2%, n = 3). Eight patients (5.9% of admitted patients) died during their inpatient hospitalization (Table 3).

increased in synchrony with the increasing number of yearly days equal to or above 105 °F. We observed a notable uptick in the number of days equal to or above 105 °F, which corresponded with an increase in total cases per year between 2018–2023. LIMITATIONS This study has several limitations that must be acknowledged to contextualize the findings and guide future research. This study was a retrospective chart abstraction and depended on existing medical records. The quality of clinical data, including the home medication list, was limited by programmed EHR extraction. Reliance on diagnostic codes to identify heat illness underestimates its incidence due to variability in physician coding. We suspect that recency bias also plays a role in the number of cases presenting and identified over time, with increasing average temperatures over the study period and the introduction of a cold-water immersion protocol in 2018. Given the large number of heatrelated deaths reported in Maricopa County, and with recent emergency medical services collaboration, we understand that our medical center treats, at most, approximately one-third of the patients being transported in the downtown metro area of Phoenix. In addition, subsequent efforts to identify heat

Climate Trends and Frequency of Heat-related Illness Most study patients presented within the meteorological summer months of June–August, with a few outliers presenting in the shoulder seasons of May and September. Over the study period, the number of cases per year gradually Volume 27, Supplement: November 2026

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12 Year Case Series of Patients Diagnosed with Heat Illness in the Southwest Table 2. Comorbid conditions and medications of patients in a study of of heat illness and heat-related deaths.

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Table 3. Clinical course of patients in study of relationship between rising temperatures and heat-related illnesses. Required ED intubation

Comorbid conditions

35.5% (n = 50)

ED disposition

Past medical history Cardiovascular

33.3% (n = 47)

Discharged

4.3% (n = 6)

Respiratory

8.5% (n = 12)

Admitted

95.7% (n = 135)

Diabetes

8.5% (n = 12)

Deceased

0% (n = 0)

Obesity

8.5% (n = 12)

Substance use

22.0% (n = 31)

Time to admission if admitted (median, IQR)

5 hours 19 minutes (1hr 22min-22hr 16min)

Hospital admission level of care

95.7% (n =135)

Co-occurring diagnoses Altered mental status

5.7% (n = 8)

Contact burns

38.3% (n = 54)

Rhabdomyolysis

25.5% (n = 36) 12.8% (n = 18)

Antihistamine

17.0% (n = 24)

Antipsychotic

22.0% (n = 31)

Benzodiazepines

7.8% (n = 11)

Beta blockers

15.6% (n = 22)

Calcium channel blockers

15.6% (n = 22)

Diuretics

10.6% (n = 15)

Laxatives

24.1% (n = 34)

Lithium

11.3% (n = 16)

SSRI

1.4% (n = 2)

TCA

1.4% (n = 2)

Progressive/Step down

25.9% (n = 35)

ICU

45.9% (n = 62)

Median (range)

2 days 18hr 42min (9hr 54 min-63d 18hr 30min)

Neuro status if alive on disposition Neuro intact

94.0% (n = 125)

Hospital disposition

Weight loss medication 0.7% (n = 1) SSRI, selective serotonin reuptake inhibitor; TCA, tricyclic antidepressant.

Self-care

59.3% (n = 80)

Behavioral health

5.9% (n = 8)

Custody

2.2% (n = 3)

Rehab

0% (n = 0)

SNF

26.7% (n = 36)

Deceased

5.9% (n = 8)

Return ED visits 0-30 days

6.4 (n = 9)

31-60 days

3.6 (n = 5)

61-90 days

0% (n = 0)

ED, emergency department; ICU, intensive care unit; SNF, skilled nursing facility; IQR, interquartile range.

illness cases by other methods or parameters suggest that identification by diagnostic code significantly underestimates the burden of disease at our medical center. Finally, including burn ED presentations and excluding the extremes of age (< 18 and > 89 years of age) under-represents the full spectrum of susceptibility and response to heat illnesses across all age groups and limits generalizability.

illness, or physicians are less likely to code this population as experiencing a heat illness. Heat injury patterns such as occupational exposure, unsheltered status, concomitant use of mind-altering substances, the use of stimulants that increase metabolic heat, as well as housing vulnerabilities such as the use of prefabricated homes or unstable access to adequate utilities, may contribute, as highlighted in the annual Maricopa County Heat Death reporting.3 Similar investigations among local universities, including a white paper in 2024 from the University of Arizona, highlight homelessness, drugs, social isolation, and lack of air conditioning as significant vulnerabilities.15 To the extent that risk factors could be reliably measured among this cohort, demographics among those affected by heat illness are comparable to population data published by Maricopa Public Health. There is consistency between this cohort regarding

DISCUSSION This observational study reviews a sizeable cohort of 141 patients with heat-related illness who were most acutely and severely ill over a 12-year period, which represents a unique perspective. Male and non-Hispanic patients comprised a higher proportion of our study population than the general ED population. Specifically, Native American patients were over-represented in our heat-illness cohort. Disparities among subgroups are hypothesis-generating and require further investigation by delineating whether this subgroup successfully employs tactics to avoid heat injury, does not present to the ED when they experience a heat Western Journal of Emergency Medicine

28.1% (n = 38)

Length of hospital admission

Medications Anticholinergic

Med/Surg

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12 Year Case Series of Patients Diagnosed with Heat Illness in the Southwest

indicators of substance use disorder. Additional cross-sectional detail is available from this cohort on the co-occurrence of the prescription of medications typically used in the treatment of mental health. The most reported home ZIP codes for patients affected by heat illness represent areas spatially adjacent to our medical centers, with even greater representation of the local ZIP codes than in the comparator population. Further investigation of local climate and demographic data, along with multicenter expansion of the study, would further clarify whether these observations relate to higher incidence or risk vs more frequent presentation or identification bias. The T67 ICD-10 diagnosis code family is diverse; this cohort is a high-acuity representation, with most (95.7%) requiring admission, and more than a third (45.9%) of admitted patients requiring intensive care level of service. Despite the acuity, the mortality in this heterogeneous group of 5.9% falls behind cited heat stroke mortality rates between 15-71%, and is more comparable to specific mortality rates for rapidly treated exertional heat stroke.13 Heat-related illness is typically described with significant morbidity, and 26.7% of patients in our cohort required skilled nursing care after their hospital discharge. Our cohort also required significant resources while in the ED, spending on average 5 hours and 19 minutes in the ED before being admitted, with 35.5% requiring ED intubation. Our cohort suggests encouraging functional outcomes, with 67.4% surviving their hospitalization and not requiring SNF placement. While our chart review reports 94% were neurologically intact at the time of disposition, more detailed and accurate measures of functional status are likely necessary, as close to one-fourth of patients with heat stroke (34.4%) suffered long-standing neurological deficits in a 2018 Australian case series.17 The total number of patients captured by diagnostic code data is likely to be lower than the total number of patients facing heat illness. Given that climate change continues to intensify, clinicians and public health officials need to find more reliable ways to monitor heat illness. We are aware of a limited and growing number of sizeable cohorts described with heat illness, most of which have limited clinical data. This study provides a unique perspective with demographic detail and outcome measures and is more nuanced than prior studies.18,19 This cohort largely corroborates observational data previously published on heat-illness risk factors.20,21 While vulnerable populations are more predisposed to heat illness due to multifactorial reasons, further investigation into social risk factors of patients affected by heat illness should be a focus for public health surveillance and population outreach to both patients and clinicians.

over 12 years, including patients presenting to the emergency department and found to have a heat-related illness, provides new clinical details among this sizable cohort. It highlights fundamental gaps in identifying and collecting of data in affected populations. This review provides a new perspective on previously published population data and provides limited clinical detail from the emergency medicine perspective, with the ED often serving as a social safety net.

Address for Correspondence: Megan McElhinny MD MPH, Valleywise Health Center, 2601 E Roosevelt Street 262-627-0038, Phoenix, AZ zip. meganlmcelhinny@gmail.com. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 McElhinny et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES 1. Davidson O. Warming world, deadly problem: Heat-related deaths are surging » Yale climate connections. 2024. Available at: http:// yaleclimateconnections.org/2024/10/warming-world-deadly-problemheat-related-deaths-are-surging/. Accessed Jun 17, 2025. 2. Iverson SA, Gettel A, Bezold C, et al. Heat-associated mortality in a hot climate: Maricopa County, Arizona, 2006-2016. Public Health Rep. 2020;135(5):631–639. 3. Batchelor M. 2023 Heat Related Deaths Report. 2024. Available at: https://www.maricopa.gov/ArchiveCenter/ViewFile/Item/5820. Accessed July 2025. 4. National Weather Service. 2022 climate year in review for Phoenix, Yuma, and El Centro. Weather.gov 2022. Available at: https://www. weather.gov/psr/yearinreview2022. Accessed Jul 11, 2024. 5. Vaidyanathan A, Malilay J, Schramm P, et al. Heat-related deaths United States, 2004-2018. Morb Mortal Wkly Rep. 2020;69(24):729– 734. 6. US Department of Commerce. Weather related fatality and injury statistics. Available at: https://www.weather.gov/hazstat/. Accessed Aug 2, 2024. 7. Sorensen C, Hess J. Treatment and prevention of heat-related

CONCLUSION As extreme heat events become more frequent and intense, our patients, practitioners, and healthcare systems must anticipate, adapt, and act swiftly. Our cohort, collected Volume 27, Supplement: November 2026

illness. N Engl J Med. 2022;387(15):1404–1413. 8. Gilbert EH, Lowenstein SR, Koziol-McLain J, et. al. Chart reviews in emergency medicine research: Where are the methods? Ann Emerg Med. 1996;27(3):305-308.

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12 Year Case Series of Patients Diagnosed with Heat Illness in the Southwest 9. von Elm E, Altman DG, Egger M, et al. The Strengthening the

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statement: guidelines for reporting observational studies. J Clin

16. Vicario SJ, Okabajue R, Haltom T. Rapid cooling in classic

Epidemiol. 2008;61(4):344-349.

heatstroke: effect on mortality rates. Am J Emerg Med.

10. Kaji AH, Schriger D, Green S. Looking through the retrospectoscope:

1986;4(5):394–398.

reducing bias in emergency medicine chart review studies. Ann

17. Lawton EM, Pearce H, Gabb GM. Review article: Environmental

Emerg Med. 2014;64(3):292-298.

heatstroke and long-term clinical neurological outcomes: a literature

11. Arizona Public Health Association. Maricopa County heat deaths

review of case reports and case series 2000-2016. Emerg Med

in 2023: a crisis for the homeless & a call for housing reform –

Australas. 2019;31(2):163–173.

AZ Public Health Association. 2024. Available at: https://azpha.

18. Conaty SJ, Ghosh S, Ashraf K, et al. Heat illness presentations

org/2024/06/27/maricopa-county-heat-deaths-in-2023-a-crisis-for-the-

to emergency departments in Western Sydney: surveillance for

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12. Kenny GP, Yardley J, Brown C, et al. Heat stress in older

Res Pract. 2023;33(4):3342331.

individuals and patients with common chronic diseases. CMAJ.

19. Rublee C, Dresser C, Giudice C, et al. Evidence-based heatstroke

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Volume 27, Supplement: November 2026

Climate Change: Original Research

Impact of Emergency Department Intravenous-Fluid Conservation Strategies During a National Shortage: Multisite Retrospective Study Hannah Moreira, MD, MPH* Ross McCormack, MD* Cecilia Sorensen, MD*† Brandon Mallory, MD*

*New York Presbyterian/Columbia University Irving Medical Center, Department of Emergency Medicine, New York, New York † Columbia University, Mailman School of Public Health, Department of Environmental Health Sciences, New York, New York

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted July 17, 2025; Revision received October 17, 2025; Accepted October 28, 2025 Electronically published January 26, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.49038

Introduction: Effective disaster response in healthcare depends on coordinated strategies that maintain access to critical supplies across institutions. During Hurricane Helene in September 2024, a major intravenous (IV) fluid shortage caused by the destruction of a manufacturing plant exposed the vulnerability of centralized supply chains. Our objective in this study was to evaluate the impact of a multisite IV fluid conservation initiative on ordering patterns, cost, and environmental outcomes across three emergency departments (ED). Methods: We conducted a retrospective study evaluating large-volume, IV fluid-bolus orders placed before, during, and after the critical shortage. Interventions included an interruptive alert in the electronic health record, clinician education, and workflow adjustments. Our primary outcome measure was the number of IV fluid-bolus orders placed during each period. Secondary outcomes included total fluid volume administered, total cost of fluids, estimated carbon dioxide emissions, and the proportion of ED encounters involving fluid administration. Results: During the pre-shortage period, 24,251 IV fluid-bolus orders were placed across 41,752 ED encounters (41.8%). Orders dropped to 18,692 during the critical shortage across 39,840 encounters (30.8%), reflecting a 22.9% relative reduction. In the post-shortage period, 23,911 orders were placed across 40,967 encounters (39.6%), remaining slightly below baseline. Estimated cost savings during the shortage period totaled $27,202, with a projected annual savings of $108,808. Carbon dioxide emissions dropped by 3.1 metric tons—the equivalent of avoiding the use of over 349 gallons of gasoline. Conclusion: Emergency department-based conservation strategies were associated with measurable reductions in IV fluid use, cost, and environmental impact. Further validation is needed to understand their impact on clinical outcomes and healthcare system resilience. [West J Emerg Med. 2026;27(6.1)61–67.]

INTRODUCTION The stability of the United States’ healthcare supply chain is essential for effective emergency medical response, yet it faces mounting pressure from escalating climaterelated disasters. Extreme weather events are becoming more frequent and severe due to climate change, with hurricanes, wildfires, flooding, and compound climate shocks posing Volume 27, Supplement: November 2026

increasing threats to critical infrastructure.1 The American College of Physicians has recommended that the healthcare community throughout the world engage in environmentally sustainable practices and support efforts to mitigate and adapt to the effects of climate change.2 There are projections that the increased trajectory of climate change can lead to increased morbidity and mortality, along with decreased 61

Western Journal of Emergency Medicine

Impact of ED IV-Fluid Conservation Strategies During a National Shortage worker productivity.3 These climate-driven disruptions can also rapidly compromise the medical supply network, creating dangerous shortages of vital resources, such as intravenous (IV) fluids, that healthcare clinicians depend on for patient treatment across various medical settings. In response to the increasing intensity of climate disasters, healthcare systems must strengthen supply chain resilience to safeguard uninterrupted access to essential medical supplies.4 In response to mounting climate challenges, global and national health authorities are developing frameworks to strengthen healthcare system resilience. The World Health Organization has established a comprehensive operational framework with 10 key components for building climateresilient health systems, emphasizing the dual responsibility to both prepare for climate impacts while reducing healthcare’s carbon footprint, which currently accounts for approximately 5% of global greenhouse gas emissions (GHG), and nearly 10% of all GHG emissions in the US.5,6 Complementing these international efforts, the US Department of Health and Human Services (HHS) has developed its own climate resilience initiatives through the Administration for Strategic Preparedness and Response, including guidance for healthcare organizations on developing climate resilience plans that address infrastructure vulnerabilities, community partnerships, and protection of at-risk populations.7 Central to both frameworks is the recognition that healthcare supply chains are integral components of resilient health systems. As part of its CARES (Climate Action, Resilience, and Equity Solutions) Pledge, HHS asked healthcare organizations to conduct an inventory of their supply chain emissions by the end of 2024 and collaborate with international partners on mitigation strategies. This reflects a broader shift toward a multidisciplinary approach to healthcare resilience—one that extends beyond emergency preparedness to include proactive climate risk assessment, supply chain diversification, and community-wide adaptation to maintain access to essential medical supplies during climate-related disruptions. These climate resilience frameworks have become increasingly urgent as real-world events demonstrate the vulnerability of healthcare supply chains to extreme weather. Two recent disasters—Hurricane Maria in September 2017 and Hurricane Helene in September 2024, both Category 4 storms—led to critical nationwide shortages of IV fluids, exemplifying the risks of a highly centralized medical supply chain. When Hurricane Maria struck Puerto Rico, it caused severe damage to Baxter International’s manufacturing facilities, which supplied a significant share of the smallvolume saline bags used in the US. This disruption led to widespread shortages across US hospitals, prompting the adoption of emergency conservation measures such as administering IV push antibiotics and oral rehydration strategies.8,9 In 2024, Hurricane Helene severely damaged Baxter International’s North Cove facility in North Carolina— Western Journal of Emergency Medicine

Moreira et al. Population Health Research Capsule

What do we already know about this issue? Intravenous (IV) fluid shortages disrupt emergency care. Conservation strategies can preserve supply and reduce waste during national crises. What was the research question? Did large-volume IV fluid use decrease during the national shortage following implementation of communication strategies to reduce unnecessary IV fluid-bolus orders? What was the major finding of the study? Large-volume IV fluid-bolus orders fell from 41.8% of ED visits before, to 30.8% during the IV fluid shortage, potentially saving $109,000 per year 3.1 metric tons of CO2 emissions. How does this improve population health? System-level conservation reduces resource use and emissions, improving health system sustainability and preparedness for future shortages.

the largest manufacturer of IV fluids in the US, which produces about 60% of IV fluids used by US hospitals,10 leading to an immediate nationwide shortage.11 In response, the US Centers for Disease Control and Prevention issued a Health Alert Network advisory to encourage IV fluid conservation.12 The American Society of Health-System Pharmacists published clinical guidance to help hospitals manage IV fluid shortages.13 Hospitals around the country quickly pivoted to create reduction protocols. Through the creation of an incident command structure, tiered communication huddles, and service line clinical practice guidelines, Intermountain Health achieved a 32% reduction across 34 sites within five weeks.14 University hospitals in Cleveland cut IV fluid use by 65%, surpassing a 40% reduction target.15 Our institution published a critical shortage alert, highlighting the need to reduce IV fluid use by 50% and provided several mitigation strategies (Figure 1). In this paper we focus on the ED and one mitigation strategy, minimizing bolus fluids, a common intervention in the ED. Conservation efforts focused on clinical decision-making and electronic health record (EHR) behavior. An interruptive alert was launched in our EHR (Epic Systems Corporation, Verona, WI) on October 17, 2024, requiring acknowledgment before proceeding with IV fluid-bolus orders. There were also frequent reminders during morning huddles to avoid unnecessary IV fluid use and 62

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Moreira et al.

Impact of ED IV-Fluid Conservation Strategies During a National Shortage

Limit continuous IV fluids Change IV medications to oral Give medications as an IV push Minimize bolus fluids Use oral hydration Use oral electrolyte repletion Assess the need to initiate “keep vein open” (KVO) orders and the need to continue those orders at every shift change, as well as reduce the KVO fluid rate to the lowest rate. Figure 1. Mitigation strategies to limit intravenous fluid conservation when clinically appropriate during the national IV fluid shortage in October 2024. IV, intravenous.

consider oral rehydration when patients are able to tolerate it.

deactivation of the interruptive alert) We conducted a chi-square test of independence to assess whether the proportion of ED encounters involving large-volume IV fluid orders differed significantly across the study periods. The primary outcome was a binary measure: the presence or absence of a large-volume IV fluid order, defined as 500 mL or 1,000 mL of normal saline or lactated Ringer solution. All statistical analyses were performed using GraphPad Prism v10.5.0 (GraphPad Software, San Diego, CA), with statistical significance defined as P < .05. The interruptive alert (Figure 2) required clinicians to confirm the necessity of IV fluids before ordering them and encouraged oral hydration when clinically appropriate. This intervention was paired with enterprise and department-wide communications, including email updates and clinical huddles. We identified orders for an oral hydration order introduced during the shortage period. Volume administered was not recorded in the EHR. Cost Analysis: We estimated unit costs using the wholesale acquisition costs (WAC) obtained through a search

METHODS We conducted a retrospective analysis of large-volume IV bolus orders placed for adult patients (> 18 years) in three EDs between July 19, 2024–April 14, 2025. We included all patient encounters with large-volume (500 mL or 1,000 mL) bolus orders of either normal saline or lactated Ringer solution. Clinical orders placed during the ED visit were extracted from the Epic Clarity database. Distinct encounters were identified by contact serial numbers. We used descriptive statistics to compare the volume of IV fluids, associated costs, and estimated emissions across three time periods. Changes in proportions were expressed as relative percentage change, weighted by site-level patient encounter volumes. The study period was divided into three time frames: - Pre-shortage: July 19–October 16, 2024 - Critical shortage: October 17, 2024–January 14, 2025 (defined by initiation of the interruptive alert) - Post-shortage: January 15–April 14, 2025 (defined by the

Figure 2. Interruptive alert in the electronic health record, prompting clinicians to justify intravenous fluid use based on a defined list of clinical indications.

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Western Journal of Emergency Medicine

Impact of ED IV-Fluid Conservation Strategies During a National Shortage on Micromedex RED BOOK (Merative, Ann Arbor, MI).16 The WAC was used as a proxy for estimated market cost because institutional negotiated prices are proprietary and could not be disclosed. The WAC for 0.9% sodium chloride was $4.22 per 500-mL bag and $4.92 per 1,000-mL bag. For lactated Ringer, the WAC was $4.61 per 500-mL bag and $5.16 per 1,000-mL bag. To simplify the cost analysis, we averaged the WAC values for sodium chloride and lactated Ringer solution by volume and rounded to the nearest whole dollar. A unit cost of $4 was used for 500-mL bags, and $5 for 1,000-mL bags. Environmental impact: We used life-cycle estimates of greenhouse gas emissions to calculate environmental burden: 390 grams (g) carbon dioxide (CO₂) per 500-mL bag and 580 g CO₂ per 1,000-mL bag. These values were obtained using published life-cycle data.17 No differences in emissions were assumed between lactated Ringer solution and normal saline. We incorporated relevant methodological principles described by Worster and Bledsoe (2005),18 including the use of clear inclusion and exclusion criteria, a consistent case definition for eligible encounters, and standardized data abstraction from the EHR. This study was reviewed and approved by the Columbia University Irving Medical Center Institutional Review Board (IRB# AAAV7300) and was conducted in accordance with ethical standards for human subjects research. All data were de-identified before analysis.

Figure 3. Total intravenous fluid orders by period and volume, reflecting changes in emergency physicians’ ordering behavior in response to shortages.

shortage period. The total volume administered was not captured. Cost dropped from $115,873 in the pre-shortage period to $88,671 during the shortage, reflecting decreased IV fluid use and yielding a short-term savings of $27,202 (Figure 4). If sustained, this reduction would project to approximately $108,808 in annual cost savings. Environmental impact decreased correspondingly. Intravenous fluid-related CO₂ emissions fell from 13 metric tons in the pre-shortage period to 9.9 metric tons during the critical shortage, a 3.1 metric ton reduction (Figure 5). This is equivalent to eliminating the emissions of more than 349 gallons of gasoline.19

RESULTS During the pre-shortage period, 24,251 IV fluid-bolus orders were placed across the three EDs. Orders dropped to 18,692 during the critical shortage, reflecting a 22.9% reduction. In the post-shortage period, orders rebounded to 23,911 but remained slightly below baseline (Figure 3). The reduction in IV fluid use was more pronounced among 1,000-mL bolus orders (-26.3%) compared with 500-mL bolus orders (-11.0%) during the shortage period, indicating that conservation efforts primarily affected larger volume infusions. Large-volume IV fluids were ordered in 41.8% of ED encounters during the pre-shortage period, declining to 30.8% during the shortage period, and increasing to 39.6% in the post-shortage period (Table 1). The variation in ordering rates across these periods was statistically significant (χ² = 1,181.0, P < .001). This relative reduction of 26.3% indicates a marked change in clinician behavior during the shortage. Following the resolution of the IV fluid shortage, this proportion rose to 39.7%, partially rebounding toward baseline. Compared to the pre-shortage period, the post-shortage proportion reflects a sustained relative reduction of 5.5%. These findings suggest a substantial and immediate shift in clinician behavior during the crisis, with evidence of some changes persisting after the acute intervention period. Use of the oral hydration order was limited: 0 orders in the pre-shortage period; 30 during the shortage; and 23 in the postWestern Journal of Emergency Medicine

Moreira et al.

DISCUSSION Our goal in this study was to assess the impact of an EHR-based interruptive alert and related interventions on IV fluid use, cost, and environmental emissions during and after a national shortage triggered by Hurricane Helene. Our findings also explore how these conservation strategies might support long-term improvements in healthcare sustainability and climate resilience. This study demonstrates that targeted conservation interventions are associated with rapid and substantial reductions in IV fluid use. The 22.9% drop in large-volume IV bolus orders observed during the critical shortage period, along with a sustained 5.5% relative reduction post-shortage, suggests that even shortterm behavioral nudges, validated here through statistically significant changes, can have a durable impact on clinical practice. Conservation strategies during a critical shortage may offer guidance for long-term change. Typically, conservation strategies prioritize critical care environments, including the ED. Our findings show that communication prompting clinicians to evaluate the clinical necessity of IV fluids, 64

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Moreira et al.

Table 1. Proportion of emergency department encounters involving large-volume intravenous fluid orders by study period. Time period

Total encounters

Encounters with fluids

Encounters without fluids

Proportion with fluids

Pre-shortage

41,752

17,466

24,286

41.8%

Shortage (interruptive alert active)

39,840

12,255

27,585

30.8%

Post-shortage

40,967

16,207

24,760

39.6%

Figure 4. Total cost of intravenous fluids by period and volume across the study period.

Figure 5. Carbon dioxide emissions from intravenous fluid use by period and volume.

was associated with a meaningful reduction in use, even in emergency settings; however, the clinical impact of these reductions remains unknown. Reflexive reliance on IV hydration remains widespread and can contribute to fluid overload, electrolyte imbalances, unnecessary resource utilization, prolonged length of stay, and increased nursing workload—without improving patient outcomes.20-22 Reducing inappropriate use can improve both patient safety and departmental efficiency. Recent IV fluid shortages have exposed the fragility of centralized medical supply chains, particularly when production is concentrated in a limited number of domestic or offshore sites. Improving resilience requires strategies such as diversifying suppliers, expanding production capacity, and strengthening public-private coordination.23 Our findings build on this effort by highlighting the importance of in-hospital conservation strategies, which can support broader efforts to prepare for and manage future supply disruptions.

negotiated insurance prices around $70, and uninsured cash rates near $114.24 Adding this perspective makes the potential impact of reduced utilization even more economically relevant, particularly for health systems and patients navigating high-cost care environments. Moreover, although outside the scope of this analysis, IV fluid administration also affects nursing workload, requires additional supplies, and may impact length of stay. Our statistical approach was partially limited to descriptive analyses, including relative percentage changes across predefined time periods. The absence of a control group limits our ability to isolate the effects of the interruptive alert and associated interventions from other concurrent system-wide changes. We cannot exclude the possibility that clinicians had already begun conserving IV fluids before the interruptive alert. Additionally, our reliance on EHR data may under-represent fluid orders that were discontinued or not administered. Moreover, we did not adjust for potential confounders, including seasonal variation or patient acuity, all of which could influence ordering patterns. This analysis did not evaluate associations between IV fluid use and patient outcomes, as defining, extracting, and interpreting such data retrospectively was beyond the scope of this study. The focus instead was on system-level resource metrics. As a result, we could not determine whether the reduction in IV fluid use affected clinical outcomes, either

LIMITATIONS Our cost analysis uses the WAC, which is set by the manufacturer and generally exceeds the actual cost hospitals pay after contract negotiations. However, this approach does not reflect the full cost of IV fluid use, which extends beyond product pricing. A national review of hospital pricing data found that a single 1,000-mL bag of normal saline could carry Volume 27, Supplement: November 2026

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Impact of ED IV-Fluid Conservation Strategies During a National Shortage

Moreira et al.

Table 2. Intravenous fluid usage, cost, and environmental impact by study period. Pre-shortage period bolus volume (mL)

Number ordered

Volume cost ($)

Total cost ($)

Grams CO2 emissions per order

500

5,382

21,528

390

2,098,980

2,691

1,000

18,869

94,345

580

10,944,020

18,869

Combined (1,000 and 500)

24,251

13,043,000

21,560

Total grams CO2 emissions

Total fluid volume given (L)

Pre-shortage period:

115,873

Shortage period: 500

4,789

19,156

390

1,867,710

2,394

1,000

13,903

69,515

580

8,063,740

13,903

Combined (1,000 and 500)

18,692

9,931,450

16,297

88,671

Post-shortage period: 500

5,677

22,708

390

2,214,030

2,838.5

1,000

18,234

91,170

580

10,575,720

18,234

Combined (1,000 and 500)

23,911

12,789,750

21,072

113,878

CO2, carbon dioxide.

positively or negatively. Notably, there was no intervention requiring IV fluid administration to deviate from standard clinical indications, and all treatment decisions were made at the discretion of the treating clinician. While an oral hydration order was introduced during the shortage it was used infrequently, and volume administered was not recorded. Oral rehydration was encouraged in the interruptive alert, but it did not direct the clinician to place an oral rehydration order. We were, therefore, unable to evaluate whether oral rehydration served as a meaningful clinical substitute for IV fluids.

who developed and implemented the EHR-based interruptive alert and hospital-wide mitigation strategies during the critical IV fluid shortage period. Their coordinated response enabled timely and effective conservation efforts across our sites.

Address for Correspondence: Hannah Moreira,MD, Columbia University Irving Medical Center, Department of Emergency Medicine 622 West 168th Street, VC-260 New York, NY 10032. Email: hm2660@cumc.columbia.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare.

CONCLUSION Conservation strategies implemented during a crisis can drive measurable and sustained reductions in IV fluid use. Future work should explore how such approaches can be extended beyond acute periods and applied to other resource-intensive areas of hospital operations. Further studies should assess the impact of IV fluid conservation on patient outcomes, including need for admission, length of stay, return visits, symptom improvement, and adverse events such as pulmonary edema and electrolyte abnormalities.

Copyright: © 2026 Moreira et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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ACKNOWLEDGMENTS We would like to thank the Columbia University Emergency Department Informatics team for their vital support in extracting IV fluid-bolus order data from the EHR system. We also acknowledge the contributions of the New York-Presbyterian clinical leadership and operations teams Western Journal of Emergency Medicine

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Western Journal of Emergency Medicine

Narrative Review

US Emergency Department Use and Operations Amid Natural Disasters: A Narrative Review Atrik Patel, MPH* Ashley A. Foster, MD† Erica Y. Popovsky, MD‡ Andrea Fawcett, MLIS§ Jennifer A. Hoffmann, MD, MS‡

*Northwestern University Feinberg School of Medicine, Chicago, Illinois † University of California, San Francisco, Department of Emergency Medicine, San Francisco, California ‡ Northwestern University Feinberg School of Medicine, Ann & Robert H. Lurie Children’s Hospital of Chicago, Division of Emergency Medicine, Department of Pediatrics, Chicago, Illinois § Ann & Robert H. Lurie Children’s Hospital of Chicago, Department of Clinical and Organizational Development, Chicago, Illinois

Section Editor: Mark I. Langdorf, MD, MPHE Submission history: Submitted July 25, 2025; Revision received November 25, 2025; Accepted November 16, 2025 Electronically published February 22, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.49118

In the United States from 2014-2024, an average of 18.2 national disasters per year caused over a billion dollars in inflation-adjusted damage, compared with 3.3 national disasters per year during the 1980s. The increased frequency and intensity of severe weather phenomena—attributed by climate science experts to climate change—have raised concerns about national emergency preparedness. One aspect of emergency preparedness is the functioning of emergency departments (ED). In this narrative review, we examine patterns of ED use and operations amid natural disasters in the US, with a special focus on vulnerable populations. The review highlights studies comparing ED use patterns between periods of disaster and non-disaster for specific disaster types, including hurricanes, wildfires, floods, winter storms, and earthquakes, as well as studies that identify disaster-mediated changes in ED visits among specific populations, including the elderly, individuals experiencing homelessness, children and youth with special health care needs, and individuals with chronic medical and psychiatric conditions. Finally, we highlight the challenges posed to EDs by these disasters, including crowding, resource scarcity, and operational strain, and proposed steps to strengthen ED preparedness for climate-related disasters. [West J Emerg Med. 2026;27(6.1)68–79.]

INTRODUCTION When reflecting on major challenges posed to communities in the 21st century, climate change stands out as a significant existential concern.1 The Intergovernmental Panel on Climate Change Sixth Assessment Report found that worsening climate conditions have increased the frequency and intensity of many weather- and climate-related extremes worldwide.2 Specifically in the United States, the number of natural disasters causing over a billion dollars in inflationadjusted damage has averaged 18.2 per year between 2014– 2024, as compared to the average of 3.3 per year during the 1980s.3 The devastating impacts of consecutive occurrences of natural disasters on a nation’s economic and social well-being

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have led to advocacy for more attention to be placed on disaster risk management.4 Following these extreme weather events, questions have arisen regarding societal readiness to mitigate the damaging effects of disasters on human health. In the US, recent trends in emergency responses have revealed concerning metrics related to the nation’s ability to handle immediate, crisis-based health challenges posed by similar surge events. During the COVID-19 pandemic, for example, many emergency departments (ED) reported issues of crowding and resource shortages that strained their ability to provide high-quality patient care.5 Given these challenges to emergency health preparedness and infrastructure due to climate-related disasters, our goal

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was to examine current patterns of ED utilization and operations in the US during natural disasters. In this review we discuss these patterns, stratified by disaster type, with particular attention to the types and timing of ED presentation that were directly linked to these natural disasters or resulted in exacerbation of existing health conditions. We describe specific population groups that may face increased susceptibility to health-related challenges requiring emergency attention due to these disasters. Additionally, we consider gaps in emergency health preparedness and response that may impact disaster management and identify steps that can be taken to fill these gaps.

Increases in the number of injuries amid hurricanes, however, are not the only impacts noted. In Long Island, a 4% increase in respiratory disease-related ED visits occurred in the days after Superstorm Sandy (October 30–November 1, 2012) when compared to preceding days (October 1–October 28) (P < .001).10 At a South Florida children’s hospital, ED visits increased 3.2% for gastroenteritis and 0.9% for cellulitis in the first and second weeks after Hurricane Andrew (1992), respectively, when compared to the week before (P < .05).11 Among New York City adults ≥ 65 years of age, EDs noted visit increases during the first week after Superstorm Sandy for cardiovascular disease (relative risk [RR] 1.10; 95% CI, 1.02-1.19); injuries and poisoning (RR 1.19, 95% CI, 1.101.28); renal disease (RR 1.44; 95% CI, 1.22-1.72); respiratory disease (RR 1.35; 95% CI, 1.21-1.49); and skin and soft tissue infections (RR 1.20; 95% CI, 1.03-1.39) compared to all other days between 2005–2014.12 Patterns of hurricane-related ED use reflect spatial differences. In 344 US counties affected by seven hurricanes (2005–2016), the magnitude of changes identified in population rates of weekly, post-hurricane ED visits by age and disease category were generally larger for counties in closer geographic proximity to the hurricane path.13 Furthermore, temporal differences in ED use patterns are noted. Compared to pre- and post-hurricane data, studies have found decreased ED use during a hurricane, likely due to individuals sheltering in place.10,14 In coastal Southeastern Virginia, six EDs experienced a 46% decline in daily visit volume on the day of Hurricane Isabel’s 2003 landfall compared to the prior six months’ daily average.15 A consequence of sheltering in place, however, is a rapid influx of ED visits immediately post-hurricane. Notably, in the five days after Hurricane Isabel’s landfall, the daily visit volume in the six studied EDs increased by 25% when compared to the same pre-hurricane daily average.15

METHODS We developed the literature search in consultation with a medical librarian (AF). Searches were performed in the following databases: PubMed; Google Scholar; Cochrane Library; CINAHL; Embase; and PsycINFO. Search queries used combinations of keywords (including “emergency department,” “climate change,” “natural disaster,” “extreme weather,” “health care delivery,” and “operations”), as well as controlled vocabulary terms. Searches were restricted to studies published in English and were not limited by publication date. For each study identified, key information was extracted, including disaster type, study characteristics, affected populations, and ED outcomes. Data extraction and inclusion decisions were conducted by the lead author, who was aware of the project hypothesis. We included studies based on relevance to US ED utilization or operations in the context of natural disasters, rather than according to prespecified inclusion or exclusion criteria. RESULTS Natural Disasters Hurricanes Due to the impact of climate change, the severity of US hurricanes has increased over the past three decades,6 raising risks of injury. In 29 counties in Eastern North Carolina, the week following Hurricane Irene (2011) saw 2,252 injuryrelated ED visits, a 22.3% increase from a 2010 reference week.7 In New Jersey, ED visits for tree-related injuries increased in the three months after Superstorm Sandy (2012) when compared to the same period during the prior year (incidence rate ratio [IRR] 1.67; 95% CI, 1.13-2.47) and subsequent year (IRR 2.47; 95% CI, 1.62-3.78).8 In the two days after the 1989 landfall of Hurricane Hugo, a daily average of 1,146 ED visits was noted in several inland North Carolina counties, a rise from the averages of two weeks prior (821 visits) and 3-14 days after (833 visits).9 Of the visit totals specific to hurricane-related concerns (comprising 30% of total ED patients in the two days after the hurricane and 10% of total patients across the rest of the study period), 88% involved injuries, with nearly half of the total disaster-related cases stemming from insect stings and wounds.9 Volume 27, Supplement: November 2026

Wildfires Climate change has intensified US wildfire seasons, which pose distinct health concerns.16 Unlike hurricanes, which elevate ED visits for injuries and other medical issues,7-12 wildfires mainly increase ED visits for respiratory and cardiovascular concerns due to smoke exposure, particularly among those with pre-existing conditions, individuals < 5 years of age, and individuals > 65 years of age.17 Visits to the ED for a range of respiratory conditions increase following wildfire smoke exposure. In June 2008, after wildfires in Eastern North Carolina, the number of ED visits rose for acute bronchitis and pneumonia (cumulative RR 1.59; 95% CI, 1.07-2.34), asthma (cumulative RR 1.65; 95% CI, 1.25-2.10), and chronic obstructive pulmonary disease (COPD) (cumulative RR 1.73; 95% CI, 1.06-2.83) in affected counties compared to referent counties.18 Because wildfire smoke can travel long distances, it represents a broad-reaching health hazard. The 69

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US ED Use and Operations in Natural Disasters in an Era of Climate Change 2023 Canadian wildfires, for instance, led to increases in ED visits for chief complaints related to asthma, COPD, or wheezing in New York City during the resulting smoke wave (June 6-8) when compared to adjacent reference days (IRR 1.44; 95% CI, 1.31-1.58).19 Studies analyzing ED usage patterns demonstrate that wildfire smoke most severely affects young children’s respiratory health.20,21 In Southern California, during the days of the 2007 wildfires, ED visits rose for dyspnea (3.2 excess visits per day; P = .01) and asthma (1.5 excess visits per day; P = .02) compared to two weeks prior.22 These fires, however, were particularly detrimental to the respiratory health of children 0-4 years of age, who presented to EDs for respiratory diagnoses at a higher rate during the peak exposure period (October 22-26) when compared to prior reference days (RR 1.70; 95% CI, 1.32-2.19).20 Similarly, during the 2017 Lilac Fire in San Diego, children 0-5 years of age had 7.3 excess daily respiratory ED visits during the fire compared to reference days from the prior year (95% CI, 3.0-11.7).21 In contrast to respiratory conditions, ED visits for cardiovascular complaints increase predominantly among the elderly,23 with delayed presentations.24 In California, wildfire smoke exposure in 2015 increased ED visits for cardiovascular diagnoses among individuals ≥ 65 years of age when compared to reference days without smoke (RR 1.15; 95% CI, 1.09-1.22).23 Furthermore, while respiratory complaints presented more immediately to EDs after California wildfire smoke events between 2016–2019, cardiovascular complications were delayed in presentation by several days.2 Wildfires may also alter care-seeking behavior for non-cardiorespiratory concerns. In California, when comparing non-federal hospital ED visits to wildfire smoke concentration estimates between 2006–2017, ED visit rates were estimated to decline for accidental injuries by 19% on high-smoke intensity days when compared to smoke-free days within the same ZIP code (95% CI, 9-30%).25 A likely contributor to this decrease may have been avoidance of care for non-urgent concerns amid poor air quality.25

control ZCTAs.27 Study of flood-exposed ZCTAs in the continental US from 2008–2017 revealed increases in number of ED visits for metabolic and kidney conditions (IRR 1.08; 95% CI, 1.06-1.11) and injuries (IRR 1.05; CI, 1.04-1.06) among individuals ≥ 65 years of age when compared to ED visits occurring four weeks prior to the events.28 After winter storms, an increase in ED visits for carbon monoxide (CO) poisoning has been observed. During the 2009 Kentucky ice storm, 202 ED visits for CO poisoning were noted, a nearly 18-fold increase from the 11 ED visits noted during the same period in the prior year.29 Increased risk for CO poisoning likely stems from exposure sources such as portable generators used during storm-related power outages.29,30 Additional concerns include potential ED visits for fall-related injuries from icy conditions,31 as well as injuries sustained from storm-associated damage.32 Earthquakes can pose challenges to EDs due to their destructive nature and unpredictable timing. Immediately following the 1994 Northridge earthquake in Southern California, ED visits to Northridge Hospital tripled (343 visits) relative to prior average daily patient volumes (110 visits), with chief presenting complaints including lacerations, contusions, and obstetric/gynecological health concerns.33 Following the 1989 Loma Prieta earthquake in Northern California, 51 hospitals in six affected counties logged 12,407 ED visits over three days, a 15% increase compared to the prior week’s baseline ED census.34 Common presenting injuries included contusions, fractures, and open wounds (Table 1).34 Vulnerable Population Elderly The elderly face disproportionate impacts from natural disasters, reflected in higher ED use. In the month following Superstorm Sandy in New Jersey, ED cases for both physical and mental health concerns for patients ≥ 65 years of age surged compared to the same reference month two years before and one year after (P < .001).35 Notably, trauma-related injuries showed the greatest rise (+ 880 cases), followed by mental illness (+ 169 cases).35 Similarly, during the three weeks after Superstorm Sandy in New York City, ED use increased by 2% in patients ≥ 85 years of age when compared to prior reference weeks (P < .01), with increased presentations of dementia (+ 1.7%), homelessness (+ 2.2%), general non-specific symptoms (+ 1.7%), and malnutrition (+ 1.3%).36 In Lower Manhattan, Superstorm Sandy resulted in a 114% increase in ED use by patients ≥ 80 years of age immediately post-disaster when compared to a pre-storm baseline visit average (P < .01), with increased presentations for dialysis, respiratory device failure, and social causes such as needing food and water (P < .05).37 After Hurricane Irma (2017), assisted living residents in Florida ≥ 65 years of age who evacuated had higher odds of ED visitation at the 30-day mark post-disaster when compared to a reference group of

Floods, Winter Storms, and Earthquakes While fewer studies have examined impacts on US EDs from floods, winter storms, and earthquakes, these events may also affect ED use patterns. In Massachusetts between 2003– 2007, analysis of ED and outpatient visits found that males had an increased risk for Clostridium difficile infection in the 7-to-13 days after coastal and flash flood events compared to reference days from four weeks before and/or after the events (odds ratio [OR] 3.21; 95% CI, 1.01-10.19).26 Flood events due to heavy precipitation have been associated with ED visit increases in affected ZIP code tabulation areas (ZCTA), as noted during the 2019 Texas flood events, which led to a 37% increase in dehydration-related visits among children 0-5 years of age (95% CI, 8%-73%) and a 45% increase among children 6-17 years of age (95% CI, 9%-92%) compared to Western Journal of Emergency Medicine

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Table 1. Summary of studies related to impacts of natural disasters on emergency department volumes in the United States. Study description

Population

Outcomes and Effect Size

Hurricanes Eastern North Carolina, Hurricane Irene (2011)7

All ED patients

Increase in injury-related ED visits (one week after disaster): • + 22.3% (reference: same week from year before disaster)

New Jersey, Superstorm Sandy (2012)8

All ED patients

Increase in tree injury-related ED visits (three months after disaster): • IRR 1.67; 95% CI, 1.13-2.47 (reference: same three months from year before disaster) • IRR 2.47; 95% CI, 1.62-3.78 (reference: same three months from year after disaster)

North Carolina, Hurricane Hugo (1989)9

All ED patients

Increase in average daily ED visits (two days after disaster): • + 325 visits (reference: two weeks before disaster) • + 313 visits (reference: 3-14 days after disaster) Large proportion of ED visits related to disaster, particularly for injuries: • Disaster-related visits = 30% of total ED volume (two days after disaster) • Disaster-related visits = 10% of total ED volume (across rest of 2-week study period) • 88% of disaster-related visits = injuries • Approximately 50% of disaster-related visits = insect stings and wounds

Long Island, Superstorm Sandy (2012)10

All ED patients

Increase in respiratory disease-related ED visits (three days after disaster): • + 4%; P < .001 (reference: 28 days before disaster)

South Florida, Hurricane Andrew (1992)11

Pediatric ED patients

Increase in gastroenteritis-related ED visits (one week after disaster): • + 3.2%; P < .05 (reference: one week before disaster) Increase in cellulitis-related ED visits (two weeks after disaster): • + 0.9%; P < .05 (reference: one week before disaster)

New York City, Superstorm Sandy (2012)12

ED patients ≥ 65 years

Increase in cardiovascular disease-related ED visits (one week after disaster): • RR 1.10; 95% CI: 1.02-1.19 (reference: all other days between 2005–2014) Increase in injuries and poisoning-related ED visits (one week after disaster): • RR 1.19; 95% CI, 1.10-1.28 (reference: all other days between 2005–2014) Increase in renal disease-related ED visits (one week after disaster): • RR 1.44; 95% CI, 1.22-1.72 (reference: all other days between 2005–2014) Increase in respiratory disease-related ED visits (one week after disaster): • RR 1.35; 95% CI, 1.21-1.49 (reference: all other days between 2005–2014) Increase in skin and soft tissue infection-related ED visits (one week after disaster): • RR 1.10; 95% CI, 1.02-1.19 (reference: all other days between 2005–2014)

344 US counties, seven hurricanes (2005–2016)13

All ED patients

Larger magnitude of changes in population rates of weekly ED visits for counties closer to path of hurricane (post-hurricane, by age and disease category)

Coastal Southeastern Virginia, Hurricane Isabel (2003)15

All ED patients

Decrease in daily ED visit volume (day of disaster): • - 46% (reference: six months before disaster) Increase in daily average visit volume (five days after disaster): • + 25% (reference: six months before disaster)

residents who sheltered in place (adjusted OR 1.16; 95% CI, 1.01-1.33).38 This finding raises further questions regarding the vulnerability of the elderly population when considering emergency preparedness and response.

diagnoses of “inadequate housing” increased 60-fold (0.2 to 12 visits), while secondary diagnoses increased nearly 40-fold (2.1 to 83 visits).38 Visits for primary diagnoses of “lack of housing” increased approximately 6-fold (2.6 to 15 visits), while secondary diagnoses increased just over 1-fold (261.1 to 289 visits).39 These increases likely reflected both pre-existing conditions of inadequate housing or homelessness and new housing insecurity or loss due to the disaster.39

Individuals Experiencing Homelessness Visits to the ED by individuals experiencing homelessness also rise after severe weather events. In the week following Superstorm Sandy, New York City saw an increase in ED visits for primary and secondary diagnoses of “inadequate housing” or “lack of housing” compared to a prior baseline weekly average (P < .01).39 Visits for primary Volume 27, Supplement: November 2026

Children and Youth with Special Healthcare Needs Across disasters, children and youth with special healthcare needs experience increased health challenges. In 71

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Table 1. Continued. Study description

Population

Outcomes and Effect Size

Eastern North Carolina, 2008 wildfires18

All ED patients

Increase in ED visits for acute bronchitis and pneumonia (affected counties): • Cumulative RR 1.59; 95% CI, 1.07-2.34 (reference: control counties) Increase in ED visits for asthma (affected counties): • Cumulative RR 1.65; 95% CI, 1.25-2.10 (reference: control counties) Increase in ED visits for chronic obstructive pulmonary disease (affected counties): • Cumulative RR 1.73; 95% CI, 1.06-2.83 (reference: control counties)

New York City, 2023 Canadian wildfires19

All ED patients

Increase in ED visits for asthma, chronic obstructive pulmonary disease, or wheezing (days of smoke wave): • IRR 1.44; 95% CI, 1.31-1.58 (reference: adjacent, non-smoke days)

Southern California, 2007 wildfires22

All ED patients

Increase in daily ED visits for dyspnea (period of disaster): • + 3.2 excess visits; P = .01 (reference: two weeks before disaster) Increase in daily ED visits for asthma (period of disaster): • + 1.5 excess visits; P = .02 (reference: two weeks prior to disaster)

Southern California, 2007 wildfires20

ED patients 0-4 years of age

Increase in ED presentations for respiratory diagnoses (period of highest exposure): • IRR 1.70; 95% CI, 1.32-2.19 (reference: control days before the disaster)

San Diego, 2017 Lilac Fire21

ED patients 0-5 years of age

Increase in daily ED visits for respiratory concerns (period of disaster): • + 7.3 excess visits (reference: control days from year before disaster)

California, 2015 wildfire smoke events23

ED patients ≥ 65 years

Increase in ED visits for cardiovascular diagnoses (periods of wildfire smoke exposure): • RR 1.15; 95% CI, 1.09-1.22 (reference: days without smoke)

California, 2016–2019 wildfire smoke events24

All ED patients

Delay in ED presentation of cardiovascular complications (periods of wildfire smoke exposure): • Several days (reference: timing of respiratory complaint presentation)

California, 2006– 2017 wildfire smoke concentration estimates25

All ED patients

Decrease in estimated ED visit rates for accidental injuries (days with high smoke intensities): • - 19%; 95% CI, 9-30% (reference: days without smoke)

Wildfires

Floods Massachusetts, 2003-2007 Male ED and out- Increase in risk for Clostridium difficile infection (7-13 days after disaster): coastal and flash flood patient patients • Odds ratio 3.21; 95% CI, 1.01-10.19 (reference: control days from four weeks events26 before and/or after disaster) Texas, 2019 flood events27

Pediatric ED Increase in dehydration-related ED visits among patients 0-5 years of age (afpatients fected ZCTAs): 0-17 years of age • + 37%; 95% CI, 8-73% (reference: control ZCTAs) Increase in dehydration-related ED visits among patients 6-17 years of age (affected ZCTAs): • 45%; 95% CI, 9-92% (reference: control ZCTAs)

Continental US, 2008– 2017 flood events28

ED patients ≥ 65 years of age

Increase in metabolic and kidney conditions-related ED visits (affected ZCTAs): • IRR 1.08; 95% CI, 1.06-1.11 (reference: four weeks before disaster) Increase in injury-related ED visits (affected ZCTAs): • IRR 1.05; 95% CI, 1.04-1.06 (reference: four weeks before disaster)

All ED patients

Increase in carbon monoxide poisoning-related ED visits (period of disaster): • + 18-fold (reference: control period from year before)

California, Northridge earthquake (1994)33

All ED patients

Increase in total ED visits (immediately following disaster): • + 3-fold (reference: average daily patient volumes before disaster) • Chief presenting complaints = lacerations, contusions, and obstetric/gynecological health concerns

California, Loma Prieta earthquake (1989)34

All ED patients

Increase in total ED visits (day of disaster and two days after disaster): • + 15% (reference: baseline ED census from week before disaster) • Common presenting injuries = contusions, fractures, and open wounds

Winter Storms Kentucky, 2009 ice storm29 Earthquakes

ED, emergency department; IRR, incident rate ratio; RR, risk ratio; ZCTA, ZIP code tabulation area.

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US ED Use and Operations in Natural Disasters in an Era of Climate Change health challenges amid natural disasters. When compared to the year prior to Superstorm Sandy, in the year after, psychiatric ED visits at Maimonides Medical Center in New York City increased by close to 32% (P < .001) (Table 2).47 Other operational New York City hospitals noted similar persisting surges in psychiatric ED visits after the storm, likely due to displaced patients from non-operational facilities.48 The consequence of these surges in visits may be longer ED boarding times for individuals seeking inpatient psychiatric care, as noted in EDs across Louisiana after Hurricane Katrina.49 In the months following this hurricane, challenges in mental health service availability were noted in New Orleans, including drops in pre-hurricane totals of practicing psychiatrists (208 to 42) and available mental health beds (487 to 190).50 Resulting strain placed on EDs that were boarding psychiatric patients is likely in part reflected in reported hospital compensation rates, with a New Orleans hospital noting a greater than 140% hurricane-related increase in uncompensated care ($17 million to $41 million), 90% of which was attributable to its ED.50

the months following Hurricane Katrina in 2005, children with chronic conditions seen in the ED, ambulatory care center, and other healthcare facilities in the New Orleans metropolitan area were more likely than children without these conditions to experience worsening asthma (16.3% vs 1.9%, P < .001), run out of medications (33.9% vs 7.9%, P < .001), and experience at the minimum one disruption in their care (58.4% vs 38.3%, P < .001).40 During disasters, children and youth with special healthcare needs can face issues accessing vital resources, such as medications40 and electrical power for life-sustaining equipment.41 In non-disaster conditions, these children and youth use EDs at a disproportionately higher rate than children without special healthcare needs, with 25.3% of this cohort visiting the ED at least one time over 12 months compared to 14.5% of children without special healthcare needs.42 Consequently, when emergency resources are strained during disasters, children and youth with special healthcare needs face additional vulnerability.41 Individuals with Chronic Health Conditions A variety of chronic health conditions may lead individuals to visit the ED because of disaster-related disruptions to care. In the weeks following Hurricane Katrina, 58% of the 21,673 total visits across 29 emergency treatment facilities in New Orleans were for illness (12,567 visits).43 Of this proportion of illness-related visits, 24.3% were attributable to chronic disease and related conditions (3,054 visits), among them 1,001 visits for cardiovascular disease, 371 visits for chronic lower-respiratory disease, and 294 visits for obstetric/gynecological conditions43 Superstorm Sandy posed threats to the health and medical needs of patients with diabetes. In the week following the storm, New York City patients with a secondary diagnosis of diabetes visited the ED in increased numbers for chronic bronchitis (+ 8 weekly cases), hypertension (+ 11 weekly cases), hypertensive kidney disease (+ 8 weekly cases), and myocardial infarction (+ 8 weekly cases) when compared to a prior weekly ED visit baseline.44 In New Jersey, an 84% increase in ED visits was noted among patients with a primary diagnosis of type II diabetes seeking acute care during the week of Superstorm Sandy when compared to a reference week from the year before (95% CI, 1.12-3.04; P = .01).45 Increased ED use by individuals with chronic conditions can also occur in the long term following natural disasters. Medicare enrollees with diabetes in Louisiana, Mississippi, Texas, and Alabama impacted by Hurricanes Katrina and Rita in 2005 had an additional 21,583 ED visits three years following the hurricanes when compared to a control group not impacted by the disasters (95% CI, 11,676 - 31,490).46

DISCUSSION Emergency Care Preparedness and Future Steps Current Landscape of Emergency Response to Natural Disasters Natural disasters result in increased strain on emergency healthcare systems nationwide, with high-risk populations such as the elderly, individuals experiencing homelessness, and individuals who may require ongoing medical attention being disproportionately impacted.35-41,43-50 This underscores the importance of ED preparedness strategies to anticipate patient surges without shifting to contingency or crisis standards of care. During natural disasters, EDs act as safety nets to address unmet healthcare needs while simultaneously providing treatment for emergent health conditions.51 Consequent crowding and patient surges, however, may constrain the ED’s ability to meet both needs.52,53 In response to scarcities in space, staffing, and resources, EDs may, therefore, transition from conventional operating conditions to operating under contingency or crisis standards of care.54 Issues of crowding are further compounded when disasterrelated hospital closures lead to operational challenges for EDs that remain open. During Tropical Storm Allison (2001), severe flooding led to the closure or service curtailment of nine Houston hospitals, reducing capacity by close to 1,700 beds.55 As a result, wait times increased to 18-21 hours in EDs still functioning.55 In this manner, hospital closures may compel individuals to seek care at EDs in place of their typical sources of medical care.56 However, as EDs may not have access to the patients’ prior medical records,57 this may present barriers to their continuity of care. Given that natural disasters exacerbate challenges, they may also affect the ability of ED staff to present to work due to competing obligations, such as addressing the

Individuals with Mental Health Symptoms Beyond immediate physical health concerns, individuals may also experience or face further exacerbation of mental Volume 27, Supplement: November 2026

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Table 2. Summary of studies related to impacts of natural disasters on vulnerable populations and their use of emergency departments in the United States. Study description

Population

Outcomes and Effect Size

New Jersey, Superstorm Sandy (2012)35

ED patients ≥ 65 years of age

Surge in both physical and mental health concern-related ED cases (one month after disaster): • P < .001 (reference: averages of control months two years before and one year after disaster) Largest increase in ED cases related to trauma-related injuries: • + 880 cases Second largest increase in ED cases related to mental illness: • + 169 cases

New York City, Superstorm Sandy (2012)36

ED patients ≥ 85 years of age

Increase in overall ED utilization (three weeks after disaster): • + 2%; P < .01 (reference: control weeks prior to disaster) Increase in dementia-related ED visits: • +. 1.7% Increase in homelessness-related ED visits: • + 2.2% Increase in general nonspecific symptoms-related ED visits: • + 1.7% Increase in malnutrition-related ED visits: • + 1.3%

Lower Manhattan, Superstorm Sandy (2012)37

ED patients ≥ 80 years of age

Increase in overall ED utilization (immediately after disaster): • + 114%; P < .01 (reference: baseline ED visit average before disaster) Increase in ED presentations for dialysis, respiratory device failure, and social causes (needing food and water): • P < .05

Florida, Hurricane Irma (2017)38

Evacuated assisted living residents ≥ 65 years of age

Increase in odds of ED visitation (30 days after disaster): • Adjusted odds ratio 1.16; 95% CI, 1.01-1.33 (reference: sheltered assisted living residents)

Elderly populations

Individuals Experiencing Homelessness New York City, Superstorm Sandy (2012)39

All ED patients Increase in ED visits for primary and secondary diagnoses of “inadequate housing” or “lack of housing” (one week after disaster): • P < .01 (reference: baseline weekly average before disaster) Increase in primary diagnoses of “inadequate housing”: • + 60-fold Increase in secondary diagnoses of “inadequate housing”: • Nearly + 40-fold Increase in primary diagnoses of “lack of housing”: • Approximately + 6-fold Increase in secondary diagnoses of “lack of housing”: • Just over + 1-fold

immediate needs of their dependents.58 Even among staff able to be present, anxieties surrounding their service may remain, including concerns about their own personal safety and the capacity of the workplace to meet their basic human needs.59 Challenges to ED resources imposed by natural disasters may further extend beyond the period during and immediately after these disasters. Disruptions to care and impacts to operations may be prolonged, as noted for EDs in New Orleans after Hurricanes Ida (2021) and Katrina (2005), which faced significant challenges addressing personnel recall and vacancies after the disasters.60,61 The ED staff who serve during and immediately after a disaster Western Journal of Emergency Medicine

may experience extended personal challenges as well, as noted among ED nurses in New Orleans who faced longitudinal symptoms of post-traumatic stress disorder after responding to Hurricane Katrina.62 Consideration must additionally be given to broader national discourse and directives that may impact emergency care efforts. For instance, the federal government has signaled intentions to downsize or dismantle the Federal Emergency Management Agency (FEMA),63 which could have implications for EDs in disaster scenarios. While FEMA does not directly manage disasters, it supports and coordinates federal resources to local systems upon a state’s request to 74

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Patel et al. Table 2. Continued Study description

Population

Outcomes and Effect Size

Children and Youth with Special Healthcare Needs New Orleans, Hurricane Katrina (2005)40

Pediatric patients seen in the ED, ambulatory care center, and other healthcare facilities

Greater likelihood of experiencing worsening asthma (months after disaster): • 16.3% vs 1.9%; P < .001 (reference: percentage of patients without special healthcare needs experiencing same) Greater likelihood of running out of medications (months after disaster): • 33.9% vs 7.9%; P < .001 (reference: percentage of patients without special healthcare needs experiencing same) Greater likelihood of experiencing at the minimum one disruption in their care (months after disaster): • 58.4% vs 38.3%; P < .001 (reference: percentage of patients without special healthcare needs experiencing same)

Individuals with Chronic Health Conditions New Orleans, Hurricane Katrina (2005)43

All emergency treatment facilities patients

Large proportion of emergency visits for illness (weeks after disaster): • 58%, 12,567 visits (reference: total emergency visits, 21,673 visits) Large proportion of illness-related visits for chronic disease and related conditions: • 24.3%, 2,054 visits (reference: total illness-related visits, 12,567 visits) Common condition = cardiovascular disease: • 1,001 visits (reference: chronic disease and related conditions-based visits, 2,054 visits) Common condition = chronic lower-respiratory disease: • 371 visits (reference: chronic disease and related conditions-based visits, 2,054 visits) Common condition = obstetric/gynecological conditions: • 294 visits (reference: chronic disease and related conditions-based visits, 2,054 visits)

New York City, Superstorm Sandy (2012)44

ED patients Increase in weekly, chronic bronchitis-related visits (one week after disaster): with secondary • + 8 cases (reference: weekly baseline visits before disaster) diagnosis of Increase in weekly, hypertension-related visits (one week after disaster): diabetes • + 11 cases (reference: weekly baseline visits before disaster) Increase in weekly, hypertensive kidney disease-related visits (one week after disaster): • + 8 cases (reference: weekly baseline visits before disaster) Increase in weekly, myocardial infarction-related visits (one week after disaster): • + 8 cases (reference: weekly baseline visits before disaster)

New Jersey, Superstorm Sandy (2012)45

ED patients with a primary diagnosis of diabetes

Increase in acute care-related ED visits (week of disaster): • + 84%; 95% CI, 1.12-3.04; P = .01 (reference: control week from year before disaster)

Louisiana, Mississippi, Texas, and Alabama, Hurricanes Katrina and Rita (2005)46

Medicare enrollees with diabetes

Increase in total ED visits (three years after disaster): • + 21,583 visits; 95% CI, 11,676-31,490 (reference: unaffected control group)

Individuals with Mental Health Symptoms New York City, Superstorm Sandy (2005)47

ED patients presenting with psychiatric concerns ED, emergency department.

Increase in psychiatry-related ED visits (year after disaster): • Close to + 32%; P < .001 (reference: year before disaster)

bolster local response capacity. Although the scope and implementation of this proposed downsizing remain uncertain, if enacted these changes could increase the operational burden on local systems by limiting their access to critical federal assistance, potentially exacerbating existing strain on EDs during disasters. Volume 27, Supplement: November 2026

Future Steps to Improve Emergency Care Delivery During and After Natural Disasters As the frequency and severity of natural disasters in the United States increase, ED disaster preparedness will be crucial. Emergency planners can use ED surveillance data to understand how previous natural disasters impacted regional 75

Western Journal of Emergency Medicine

US ED Use and Operations in Natural Disasters in an Era of Climate Change EDs to prepare for future severe weather events.64 Specific attention should further be given to creating syndromic surveillance tools that consider the impacts of natural disasters on ED visits related to mental health and psychological trauma.65 Additionally, clinical frameworks that outline how to efficiently and effectively assess and manage climate- and disaster-related health challenges can be created and distributed to ED teams.66 To better address crowding, local government and regional healthcare coalitions can make more non-ED locations available to the public and inform them about where they can receive medical treatment at these locations during disasters. For example, offering non-urgent medical screening and treatment in evacuee evaluation centers can reduce strain on local EDs.52 Official messaging regarding the utility of these spaces can be relayed to the public through social media, emergency calls, and other mechanisms of contact. In conjunction, telehealth models can be developed to connect emergency medical services (EMS) with ED staff to enhance on-scene patient assessment and intervention,67 thereby improving triage and potentially limiting unnecessary ED transports. Adequate funding to support EMS and train EMS personnel to respond to disasters is critical to the success of this model. A well-coordinated disaster response is not limited to immediate emergency response needs; it also addresses the long-term consequences of natural disasters. To rebuild emergency care capacity after disasters, for example, medical operations coordination centers can be formed to monitor patient volumes and balance the load across functioning EDs by directing patient transports based on resource availability.68 To support ED staff preparedness, ED disaster planners must account for personal concerns and staff needs that may impede their ability to respond to a disaster.58 Accordingly, emergency planning should clearly delineate the expected duties of ED staff during natural disasters, while also addressing personal or professional obstacles for staff to engage in their work.69 Furthermore, hospital administrators should offer ED staff short-term and long-term treatment options for emotional difficulties faced while handling health crises caused by natural disasters.62 Ultimately, the responsibility for ensuring that emergency health services can meet increased demands during and after natural disasters rests not solely on ED stakeholders but also on broader health systems, public health, and public service representatives. A concerted effort must be made by all groups in tandem to address the impacts of the disaster cycle through leadership in public policy and intervention,70 further research and education,70 and advocacy for greater investment in disaster readiness. Such operational, political, and academic considerations should both bolster emergency preparedness and address explicit contributors to the noted rise in the force and frequency of natural disasters, namely the worsening effects of climate change.71 Western Journal of Emergency Medicine

Patel et al.

LIMITATIONS This narrative review has several limitations. The studies were heterogeneous in design, data source, and regional focus, limiting direct comparisons. Many studies further relied on matched cohorts or retrospective designs, which may not have accounted for all confounding variables and could not rule out multifactorial influences on observed outcomes. Data on certain disasters, such as floods, winter storms, and earthquakes, as well as vulnerable populations, including rural or uninsured patients, remain sparse. Access to standardized patient-level and operational data, such as ED visit timing, acuity, resource use, and staffing, would have enhanced the discussion by enabling more detailed comparisons and clearer identification of factors associated with ED surges and care disruptions. Future multicenter, prospective, and mixed-methods studies could clarify these patterns while capturing insights from both patients and clinicians. CONCLUSION As critical access points to care, emergency departments serve as a cornerstone of disaster response and recovery. Amid the growing frequency and severity of climate-related natural disasters, it is imperative that EDs take steps to ensure they remain well-positioned to deliver operationally efficient care to meet community needs. Notably, climate-based challenges can compromise health equity. As has been detailed, a large body of data shows that the most socially and medically vulnerable are especially likely to suffer adverse outcomes and face barriers to healthcare during natural disasters. Consequently, in the face of climate change, health justice must remain the guiding compass for strengthening ED resilience and emergency care preparedness. ACKNOWLEDGMENT We gratefully acknowledge the financial support of the Grainger Research Program in Emergency Medicine at Lurie Children’s Hospital in Chicago, IL, for this work.

Address for Correspondence: Atrik Patel, MPH, Northwestern University Feinberg School of Medicine, 420 E. Superior St., Chicago, IL 60611. Email: atrik.patel@northwestern.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest to declare. Copyright: © 2026 Patel et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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US ED Use and Operations in Natural Disasters in an Era of Climate Change 17. Skinner R, Luther M, Hertelendy AJ, et al. A literature review on the

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Western Journal of Emergency Medicine

Original Research

Selected Impacts of Urban Heat Islands on Emergency Medical Services Utilization in Rhode Island Katelyn Moretti, MD, MS* Yiwen Liang, MS† John Matthew Nicklas, BSc‡ Baylor Fox-Kemper, PhD‡ Authors continued at end of article

*Warren Alpert Medical School of Brown University, Department of Emergency Medicine, Providence, Rhode Island † The University of Hong Kong, LKS Faculty of Medicine, School of Public Health, Hong Kong SAR, China

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted August 18, 2025; Revision received December 8, 2025; Accepted December 15, 2025 Electronically published April 14, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.50699

Introduction: Excessive environmental heat exposure is clearly associated with an increased likelihood that individual patients will suffer adverse health outcomes. Such heat exposure also strains healthcare systems via increased utilization, a burden which can challenge systems’ capacities. Health impacts vary geographically with urban heat islands potentially contributing to higher temperatures and greater health risks. However, those most vulnerable to this exposure are not well identified. Our objective in this novel study was to compare and quantify differences in emergency medical services (EMS) use by selected patients during hot days in Rhode Island. Patients were recruited from low socioeconomic residential locations, stratified by whether they accessed EMS from within one of the state’s “urban heat islands,” or from other locations without “heat island” effects. We also compared selected patient demographic characteristics, and other EMS run data, between events associated with EMS access from these two types of areas. Methods: This retrospective, cross-sectional cohort study evaluated how the probability of an EMS encounter varied in response to daily mean temperature and the urban heat island status of the encounter location. We aggregated EMS dispatch data, daily mean temperature, urban heat island classification and the Area Deprivation Index of the encounter location. A quasi-Poisson regression model assessed the relationship between EMS encounter frequency and potential risk factors including daily temperature, urban heat island status, year, day of the week, sex, age, and relevant interaction terms. The model was restricted to low socioeconomic, residential encounter locations to reduce confounding (noted elsewhere by year) and focus on the target population. The primary outcome was the rate ratio (RR) of EMS encounters for urban heat island locations vs locations without an urban heat island effect, in response to summer temperatures. Secondary outcomes included RRs of EMS encounters stratified by age, sex, weekday vs weekend, and year. Results: Higher temperatures were associated with increased EMS call rates across all demographic subgroups. A 5 °F (2.8 °C) increase in mean daily temperature was associated with an increase in an overall EMS encounter rate of 1.5% (RR, 1.015; 95% CI, 1.005-1.031, P = .004). On a weekday in 2021, at 75 °F degrees, 68 EMS encounters would be predicted for the residential, low socioeconomic status locations in the state while at 95 °F, 73 EMS encounters would be expected. The EMS rates were consistently higher in urban heat islands across all study years, after accounting for daily temperature, year, day of the week, demographic characteristics, population size and interactions between age, sex, urban heat island and weekday vs weekend. The largest relative increase in EMS encounters was observed in 2019, with rates 34% higher in urban heat islands compared to locations without an urban heat island effect (RR, 1.34; 95% CI, 1.27-1.42). The smallest increase occurred in 2020 (RR, 1.12; 95% CI, 1.06-1.18). Conclusion: In residential and low socioeconomic locations, living in an urban heat island increased the probability of an EMS encounter, highlighting potential compounding effects of social and environmental vulnerability. As climate change intensifies extreme heat events, locationally targeted interventions may be critical in reducing heat-related health impacts. [West J Emerg Med. 2026;27(6.1)91–97.]

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Impacts of Urban Heat Islands on EMS Use

Moretti et al. INTRODUCTION Hot weather negatively impacts humans through a variety of pathophysiological mechanisms, but not all are affected equally.1-5 First, the adverse effects of heat on health are not geographically uniform. Urban heat islands (UHI) occur because built environments (eg, parking lots, large buildings) result in hotter than average surface temperatures and contribute to intra-city temperature differences.6-10 People living in UHIs are especially susceptible to heat and heatwaves with increased hospitalizations and mortality.11-15 In Boston, Massachusetts, streets with a higher land surface temperature were more likely than cooler streets to be the sites of medical emergencies during heat advisories relative to the rate of medical emergencies during non-heat advisory periods.16 Second, patient characteristics increase risk. Older adults are particularly susceptible secondary to chronic health conditions, limited mobility, and social isolation.17-19 Individuals with lower socioeconomic status or marginalized populations face increased heat risks due to poor housing conditions, lack of air conditioning, and extended outdoor working hours. In over 96% of the largest United States (U.S.) urban areas, persons of color are more likely to live in neighborhoods with higher heat intensity than non-Hispanic White residents.20-21 Rhode Island is the fastest warming state in the contiguous U.S., having warmed 3.1 °F (1.7 °C) since 1900.22 These rising summer temperatures have been linked to more frequent emergency medical service (EMS) encounters23 and increased emergency department (ED) use in the state.24 However, prior studies have not accounted for the UHI effect or the effects of patient-level variables such as age or socioeconomic status. In this study we assessed the impacts of summer temperature variability (between June and August of 2018– 2021) on EMS utilization in Rhode Island by comparing UHI and non-UHI locations, while accounting for patient age and socioeconomic status. Understanding and anticipating fluctuations in EMS demand provides an important opportunity to strengthen preparedness and enhance climatechange adaptation within the emergency care system as summer temperatures rise. Moreover, quantifying the morbidity associated with UHIs can guide decision makers and urban planners in directing mitigation and cooling interventions toward the communities most affected.

Population Health Research Capsule What do we already know about this issue? Hot weather increases illness and emergency care use, with urban heat islands (UHI) and social vulnerability amplifying heat-related hospitalizations. What was the research question? How do UHIs affect summer emergency medical services (EMS) use in low socioeconomic status residential areas of Rhode Island? What was the major finding of the study? EMS use was up to 34% higher in UHI than in non-UHI locations (RR, 1.34; 95% CI, 1.27-1.42). How does this improve population health? By identifying heat-vulnerable communities, these findings support targeted interventions to reduce EMS demand and heat-related illness as temperatures rise.

distinct data sources: EMS utilization records; daily temperature data; urban heat severity indices; socioeconomic status metrics; census demographics; and building type classifications. These were linked using geospatial and administrative identifiers such as date, address, 9-digit ZIP code, and the 12-digit Federal Information Processing Series (FIPS) code (Supplemental Table 1). Eligible encounters were those occurring between June and August of 2018–2021 and for which the recorded location could be successfully linked to an UHI index. EMS Utilization We obtained EMS data from the Rhode Island National Emergency Medical Services Information System (NEMSIS) v3, maintained by the Center for Emergency Medical Services within the Rhode Island Department of Health. This dataset contains patient-level records of EMS encounters, including demographics and location of EMS contact.

METHODS Location Rhode Island is the smallest U.S. state by area, covering a little over 1,000 square miles, with a population of just over 1 million residents.25 The state includes a mix of dense urban centers, suburban neighborhoods, and rural areas. Most of the population resides in and around the Providence metropolitan area, where many UHIs exist.26

Temperature Data Daily minimum, maximum, and mean temperatures were retrieved from the National Centers for Environmental Information of the National Oceanic and Atmospheric Administration (NOAA), using readings from the weather station at Theodore Francis Green State Airport (now Rhode Island TF Green International) in Warwick, Rhode Island.

Database Formation We constructed an integrated dataset by merging six Volume 27, Supplement: November 2026

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Urban Heat Island Severity We measured UHI severity using raster data (grid-based spatial datasets) from the Trust for Public Land’s ParkServe map. This dataset, with a 30-meter spatial resolution, was developed from Landsat 8 Band 10 imagery obtained via the National Aeronautics and Space Administration and NOAA. We used Landsat data from 2018 were used to generate this raster map for 2018–2019 and applied updated 2020 Landsat data to 2020– 2021. This dataset provided the urban heat severity relative to the surrounding area categorized on a scale from 0-5 using the Jenks Natural Breaks classification method.27 A value of 0 indicates a location at or below the mean city temperature (non-heat island), while a score of 5 represents severe heat exposure (8-12 °F or 4-7 °C above the mean). The temperature ranges associated with each index score are presented in Supplemental Table 2. The ParkServe UHI layer has been used in prior UHI analyses and cited in public-health and urban forestry studies as a standardized, nationally consistent urban heat indicator.28,29 Socioeconomic Status We assessed socioeconomic status at the encounter location using the 2021 Area Deprivation Index (ADI v4.0.1), developed by the Health Resources and Services Administration.30 The ADI provides decile rankings (1-10) of census block groups, where 1 indicates the least deprived and 10 the most deprived, based on composite measures of income, education, employment, and housing quality.

Figure 1. Locations in which emergency medical services were linked to urban heat severity classifications. Gray dots represent encounter locations without urban heat effect, Colored dots represent encounters categorized by urban heat index, ranging from 1 (yellow; lowest severity) to 5 (red; highest severity). EMS, emergency medical services.

Population Demographics Age- and sex-specific population estimates for each census block group were obtained from the 2020 U.S. Census. These data were linked to EMS encounters using the 12-digit FIPS code.31

patient information. This study was conducted and reported in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines.

Residential Classification Each encounter location was classified as residential (house, residential, duplex, apartment) or non-residential (commercial, industrial, government, educational) using data from the Rhode Island E-911 database.32 Linkage of the UHI classification to EMS encounter address via ArcGIS PRO (Environmental Research Services Institute, Redlands, CA)33 obtained an 85% success rate with only match scores > 40 accepted. Of all matches, 95% had a match score ≥ 80. Non-matches were all secondary to incomplete addresses. Non-matched encounters were manually reviewed, and the match rate was increased to 94% (Figure 1).

Variable Characterization The final analytic dataset included the date of EMS encounter, patient demographics (age and sex), encounter location (including full address, 9-digit ZIP code, and FIPS code), UHI index at the encounter location, residential status, and the ADI score. To assess potential bias, we compared encounters excluded for insufficient data with the final analytic cohort using t-tests or chi-square tests. The decision to dichotomize both UHI status (present vs absent) and ADI scores was based on both conceptual considerations and practical limitations identified during exploratory analyses. First, EMS encounters demonstrated a clear distributional shift at the boundary between urban heat severity = 0 and urban heat severity ≥ 1. In areas with an urban heat severity score of 0, most EMS runs originated from census block groups with ADI < 7, whereas in areas with any degree of urban heat severity (≥ 1), most encounters came from areas with ADI ≥ 7 (Supplemental Table 3). This suggested that the presence of any UHI exposure—not necessarily its graded

Ethics Approval and Reporting Standards We obtained institutional review board (IRB) approval from the Rhode Island Department of Health for access to patientlevel data from the NEMSIS database (IRB 2020-08). Patient information was collected via standardized forms completed by EMS personnel for each encounter. All other datasets used in this analysis were publicly available and did not contain identifiable Western Journal of Emergency Medicine

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Moretti et al. severity—aligned with a meaningful sociodemographic shift in encounter patterns. In addition, the middle categories (ADI 4-6) did not form a stable or interpretable “medium” socioeconomic status group in our data; rather, they aligned more closely with the low-deprivation cluster (ADI 1-3). Second, the frequency of EMS encounters within higher UHI categories was low. Only 15% of encounters originated from UHI levels ≥ 2, and UHI level 5 accounted for approximately one mean daily encounter. These sparse strata substantially limited statistical power and risked unstable estimates if modeled across the full five-level UHI scale as defined by the Trust for Public Land’s ParkServe map. Given these distributional constraints and the lack of sufficient events to support a multilevel approach, we selected dichotomization to preserve model stability and interpretability. Accordingly, we categorized UHI severity as non-UHI (urban heat severity = 0) and UHI present (urban heat severity ≥ 1) at the encounter location, with the latter encompassing all non-zero urban heat severity levels (Supplemental Table 2). Socioeconomic status was similarly dichotomized into high (ADI < 7) and low (ADI ≥ 7). We dichotomized age as < 65 vs. ≥ 65 years, based on established evidence of increased heat vulnerability among older adults.20,34-36 Day of the week was classified as weekday vs weekend to account for known variations in EMS utilization.36,37 Encounter locations were classified as residential (e.g., house, duplex, apartment) or non-residential (e.g., commercial, industrial, government, educational settings). We compared cohort characteristics, including year, age group, and sex, stratified by urban heat severity and ADI scores, using Pearson’s chi-squared tests. Mean age and the proportion of residential encounters were also compared across these categories using t-tests.

designated as residential and low socioeconomic status for several reasons. First, preliminary analyses revealed that confounding by year was present in non-residential, high socioeconomic status areas (Supplemental Figure 1). Second, individuals with high socioeconomic status are less vulnerable to environmental heat exposure.17-18 Additionally, it was reasoned that non-residential areas were most affected by COVID-19,38 did not represent prolonged exposures (eg, short errands), and were primarily characterized by indoor environments such as offices, airports, and shopping centers. Therefore, to reduce confounding and focus on the primary residential population of interest, we excluded EMS encounters from non-residential or high socioeconomic status locations. To estimate the at-risk population living within UHIs in Rhode Island, we spatially joined 2020 census blocks with the 2021 UHI severity map. A census block was classified as located within an UHI if its centroid fell inside a designated heat island area. The populations of all low socioeconomic status blocks meeting UHI criteria were summed (Figure 3). Additionally, the population ≥ 65 of age within these blocks was aggregated by sex to enable age-sex stratified analysis. RESULTS Characteristics of Emergency Medical Services Encounters A total of 106,590 EMS encounters were initially identified for the summer months (June–August) across 2018–2021. After removing duplicate records and restricting to encounters matched to a verifiable urban heat index, 95,109 encounters remained. We excluded an additional 13,392 encounters because of missing 9-digit ZIP codes and inability to determine an ADI score. To ensure temporal consistency across all years, we excluded August 31, missing from the

Model Development We developed a quasi-Poisson regression model to determine the factors associated with the daily count of EMS encounters across Rhode Island. The model included patientlevel covariates for age and sex (male vs female), and geographic covariate presence of an UHI at the encounter location. Temporal variables included year and day of the week, with the latter categorized as weekend vs weekday. Temperature exposure was modeled as the daily mean temperature, consistent with prior studies demonstrating comparable associations across mean, maximum, and minimum temperature metrics in Rhode Island.23 Lagged temperature exposures (up to five days) were evaluated but not found to be significant and were, therefore, excluded from the final model. We included a log-transformed population offset to account for varying population sizes across census blocks. The model evaluated all possible interactions. Those interactions found significant were included to assess potential effect modification across time and demographic subgroups. Final analyses were restricted to encounter locations Volume 27, Supplement: November 2026

Figure 3. Baseline Populations in Rhode Island based on the 2020 census, the 2020 Trust for Public Land’s urban heat island severity layer and the 2021 Area Deprivation Index. ADI, Area Deprivation Index; UHI, urban heat island.

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2018 and 2019 datasets, from the 2020 and 2021 datasets. The remaining number of EMS encounters was 81,229. For the Poisson regression model that was restricted to encounters in residential, low-SES encounter locations, the number of encounters was 22,511 (Figure 2). We excluded a total of 13,880 encounters because they could not be linked to an ADI designation or occurred on the date of August 31 in 2020 or 2021. Compared with the included cohort, excluded encounters were less likely to originate from an UHI (55.2% vs 70.5%, P < .05), had a younger mean age (53 vs 58 years, P < .05), and had a higher proportion of males (50.8% vs 47.3%). There were no differences in the distribution of excluded encounters across study years (Supplemental Table 4). The full summer temperature range across the four years of study was 42-100 °F (6-38 °C) with the mean daily temperatures covering a 52-87 °F (11-31 °C) range. The summer of 2019 was slightly cooler on average (72.2 °F, or 22.3 °C) and 2020 was slightly warmer (73.7 °F, or 23.1 °C) (Supplemental Figure 2). The mean daily number of EMS encounters during the study period was 223 (SD 23.6) (Supplemental Figure 2). For all EMS encounters including high socioeconomic status and non-residential locations, 55% originated from areas classified as non-UHIs and 59% occurred in higher socioeconomic status areas (computable from the header row of Table 1). Encounters in UHIs were

more likely to be in low socioeconomic status areas (55%), and those without UHI effect more likely to be in high socioeconomic status areas (73%). The overall mean patient age was 58 years (SD 23). Patients outside UHIs were older (mean 60 (SD 23]) than those from UHIs (mean 56 [SD 23]). Compared to patients from urban heat islands, those outside urban heat islands were more likely to be ≥ 65 years of age (49% vs 39%) and more likely to live in high socioeconomic status areas (73% vs. 42%). A higher proportion of encounters not in UHIs occurred at residential locations (69%) vs. UHIs (65%; P < .001), and residential encounters were more common in low socioeconomic status areas (71%) than in high socioeconomic status areas (66%). Sex distribution was similar across strata, although male patients were slightly more represented in urban heat islands compared to locations without urban heat island effect (48% vs 47%). Baseline Population of Rhode Islanders Residing in an Urban Heat Island and low SES Status In 2020, the census of Rhode Island was 1,097,379. Several block groups did not have ADI values, either because the population was too small or the population lived in group quarters. This included local university campuses. These census blocks were excluded (total population excluded = 41,274). Among the remaining 1,056,106 residents, the number residing in a census track with an ADI ≥ 7 comprising the baseline population for regression was 397,369. Of those whose centroid overlapped with an UHI (urban heat severity ≥ 1 on the 2020 Trust for Public Land’s raster map) was calculated to be 227,2045 (Figure 3). Regression Analysis: EMS Encounters by Temperature, Urban Heat Island Effect, and Patient Characteristics for Low Socioeconomic, Residential Locations Higher daily average temperatures increased the daily EMS call rates to residential, low-socioeconomic status locations and for all demographic subgroups. A 5 °F (2.8 °C) increase in daily mean temperature was associated with an increase in an overall EMS encounter rate of 1.5% (rate ratio [RR] 1.015, 95% CI, 1.005-1.031, P = .004, Supplemental Table 5 where RR is reported per 1 °F increase.) To illustrate the effect on the absolute total number of EMS responses, a weekday in 2021 was selected. From 75 °F to 95 °F, EMS encounters would be expected to rise from 68 EMS encounters to 73 EMS encounters. The EMS encounter rates were consistently higher in areas classified as UHIs compared to areas outside UHIs across all study years, after accounting for daily temperature, year, day of the week, demographic characteristics, population size and interactions between age, sex, UHI, and weekday vs weekend. In 2018, EMS encounter rates in UHIs were 27% higher than in areas without UHI effect (RR, 1.27; 95% CI, 1.21-1.35, Figure 4). This disparity increased in 2019, with a

Figure 2. Cohort Selection Flow Diagram. Figure 2, This flow diagram depicts the cohort selection of EMS encounters included in the final analytic cohort, starting from 106,590 EMS encounters during summer the months (June– August) from 2018–2021, ADI, area deprivation index; EMS, emergency medical services; SES, socioeconomic status; UHS, urban heat severity.

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Table 1. Demographic and encounter characteristics by urban heat island status and area deprivation index (< 7 or ≥ 7) for all socioeconomic, non-residential and residential encounters. All percentages are calculated relative to the column header. Overall Non-UHI UHI (N = 81,229) (n = 44,847) (n = 36,382) Year

P-value (UHI)

High SES (n = 48,171)

Low SES (n = 31,734)

SES Missing (n = 1,324)

<.001

2018

21,066 (25.9%)

11,357 (25.3%)

9,709 (26.7%)

12,610 (26.2%)

8,063 (25.4%)

393 (29.7%)

2019

21,273 (26.2%)

11,506 (25.6%)

9,767 (26.9%)

12,865 (26.7%)

8,006 (25.2%)

402 (30.3%)

2020

18,312 (22.5%)

10,477 (23.4%)

7,835 (21.5%)

10,880 (22.6%)

7,186 (22.7%)

246 (18.6%)

2021

20,578 (25.3%)

11,507 (25.7%)

9,071 (24.9%)

11,816 (24.5%)

8,479 (26.7%)

283 (21.4%)

58.0 (23.3)

59.9 (23.4)

55.8 (22.9)

61.1 (23.4)

53.9 (22.3)

47.5 (21.4)

<65 yrs

45,155 (55.6%)

22,853 (51.0%)

22,302 (61.3%)

23,321 (48.4%)

20,830 (65.6%)

1,004 (75.9%)

≥65 yrs

36,018 (44.4%)

21,966 (49.0%)

14,052 (38.6%)

24,822 (51.5%)

10,877 (34.3%)

319 (24.1%)

Missing

56 (<0.1%)

28 (<0.1%)

28 (0.1%)

27 (0.1%)

1 (<0.1%)

Age Mean (SD) Age

<.001 <.001

Sex

.002

Female

23,789 (53.0%)

18,923 (52.0%)

25,459 (52.9%)

16,704 (52.6%)

549 (41.5%)

Male

38,460 (47.3%)

21,025 (46.9%)

17,435 (47.9%)

22,685 (47.1%)

15,002 (47.3%)

773 (58.4%)

Missing

57 (0.1%)

33 (0.1%)

24 (0.1%)

27 (<0.1%)

28 (0.1%)

2 (0.1%)

67.3%

69.4%

64.7%

66.1%

70.9%

23.0%

UHI

15,317 (31.8%)

20,159 (63.5%)

906 (68.4%)

Non-UHI

32,854 (68.2%)

11,575 (36.5%)

418 (31.6%)

< .001

SES

< .001 < .001

42,712 (52.6%)

% Residential Location

P-value (SES)

< .001

<.001

High

48,171 (59.3%)

32,854 (73.3%)

15,317 (42.1%)

Low

31,734 (39.1%)

11,575 (25.8%)

20,159 (55.4%)

Missing

1,324 (1.6%)

418 (0.9%)

906 (2.5%)

UHI

SES, socioeconomic status; UHI, urban heat island.

34% higher rate in UHIs (RR, 1.34; 95% CI, 1.27-1.42). Although the magnitude of association decreased slightly in subsequent years, UHIs continued to experience elevated EMS use in both 2020 (RR, 1.12; 95% CI, 1.06-1.18, Table 2) and 2021 (RR, 1.13; 95% CI, 1.07-1.19, Figure 4). Use of EMS increased substantially with higher temperatures, the presence of an UHI, and age (Figure 5). Utilization was slightly higher for females than for males, and Volume 27, Supplement: November 2026

slightly higher on weekdays than on weekends. For those < 65 of age living in a non-UHI, the associated number of EMS encounters per 10,000 people ranged between 0.8-1.1 at a temperature of 60 °F (16 °C), increasing to a range of 0.9-1.2 when the temperature reached 90 °F (32 °C). In an UHI, the rates were higher: approximately 1.1-1.2 on cool summer days and 1.3-1.4 on the warmest days. Conversely, the rates were much higher for individuals ≥ 65 years of age, ranging between 85

Western Journal of Emergency Medicine

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Moretti et al. and highlight the role of the local environment in healthcare utilization. Notably, EMS encounters were consistently higher in UHIs compared to non-UHIs, even after controlling for daily temperature and year. The strength of this association was most pronounced in 2018 and 2019, when the rate of calls was about 30% higher in heat-affected urban zones. This was despite a slightly cooler 2019 summer. Although the magnitude of the UHI effect diminished in 2020 and 2021, likely influenced by broader social disruptions and shifts in healthcare utilization related to the COVID-19 pandemic,39 the association remained statistically significant. This aligns with prior research linking UHIs with higher rates of heat-related illness, including heat exhaustion and heat stroke.40 Other disease-specific analyses, such as cardiovascular hospitalizations, have also been linked to UHIs with a 2.4% increase observed during periods of extreme heat.41 Recent systematic review and meta-analysis further found a 6% higher risk of morbidity or mortality associated with UHIs during periods of elevated ambient temperatures. However, the review’s combined morbidity estimates drew from studies focused on specific diagnoses rather than overall illness burden. On the mitigation side, a natural cooling intervention in Canada, primarily consisting of expanded green space, was associated with a 40-50% reduction in heat-related ambulance calls.42 The current study adds to this evidence base by quantifying all-cause morbidity rather than limiting the analyses to specific diagnoses and by estimating the broader burden on the EMS system of an entire state. Adaptive measures such as air conditioning (AC) have helped reduce the impact of extreme heat and have likely prevented some of the heat-related deaths that were previously projected.43-44 However, low socioeconomic status and income have been associated with limited capacity to cool built environments because of the high cost of electricity and the inability to build central cooling infrastructure.45 These vulnerable populations may instead have to rely on other interventions (ie, public buildings for AC, public pools, fans, increased hydration), which may not be feasible or effective in increasingly intense and frequent extreme heat events.46 As shown in the current analysis, EMS utilization was greater in UHIs in residential areas with lower socioeconomic status, and it further increased in response to rising summer temperatures. This clearly demonstrates the ongoing adverse health impacts of heat for vulnerable populations residing in urban heat islands.

Figure 4. Adjusted rate ratios and 95% CI for EMS encounters among residents of urban heat island (UHI) areas compared with residents outside UHIs, shown by calendar year (2018–2021). Models were adjusted for daily temperature, year, day of the week, age, sex, population size, and interactions between age, sex, UHI status, and weekday vs weekend. Values > 1 indicate higher EMS encounter rates in UHI areas relative to non-UHI areas. EMS, emergency medical services RR, rate ratios; UHI, urban heat island.

3.0-3.5 in non-UHI areas and 4.0-4.5 in UHI areas at 60 °F, to 3.0-4.5 in non-UHI areas and 4.5-5.5 in UHI areas at 90 °F. These differences translated to a wide range of rate ratios (equivalent here to relative risk) comparing use rates at a fixed temperature for different combinations of sex, age, year, time of week and UHI residence to a reference group of males, < 65 years of age, on weekdays in non-UHI areas in 2020 (Table 2). Relative risks were all > 3 for older individuals and generally < 1.3 for those < 65 years of age. They were also lower in 2020 compared with other years in UHIs. In non-UHI areas, the rates were higher in 2020 than in 2018 or 2019 but lower than in 2021. To illustrate the change in the absolute number of EMS encounters, we calculated the daily increase in encounters per 10,000 population (by subgroup) on weekdays in 2021, relative to a mean temperature of 75 °F, within residential, low socioeconomic locations. These values were then compared between areas with and without an UHI effect (Supplemental Figure 4). For example, among women > 65 years of age, an average daily temperature of 95° F (vs 75 °F) was associated with 0.3 additional EMS encounters per 10,000 people in low socioeconomic status residential locations without UHI, compared with 0.34 additional encounters in similar locations with UHI influence.

LIMITATIONS While our analysis is based on complete, statewide EMS records and official National Weather Service temperature recordings over a four-year period, our data have some weaknesses. A subset of encounters (n = 13,880) could not be linked to an ADI designation or fell on August 31, 2020, or August 31, 2021 and were, therefore, excluded from the final cohort. Comparison of these excluded encounters with the included cohort revealed small but statistically significant

DISCUSSION Encounters with EMS increase as summer temperatures increase. This effect is found within all age and sex subgroups and across all days of the week. In addition, UHI exposure is associated with increased EMS utilization across Rhode Island, specifically in residential, low socioeconomic status areas. These findings underscore the disproportionate burden of heat-related health impacts among vulnerable populations Western Journal of Emergency Medicine

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excluded group represents a population somewhat less likely to experience increased EMS utilization with rising temperatures— given younger age, male predominance, and lower representation from UHIs. Even within the subset of excluded encounters originating from UHIs, the slightly younger age and higher proportion of males could contribute to a marginally lower temperature-related increase in EMS utilization, potentially yielding a slightly lower overall rate ratio. However, these differences were relatively small and would have been accounted for in age-sex stratified analyses. Although our models adjusted for key demographic, temporal, and neighborhood-level factors, the possibility of residual confounding remains. Our Poisson models estimated average risk within age, sex, and ADI strata, rather than at the individual level. Because individual characteristics were not available for residents who did not use the EMS system, we were unable to account for person-level differences that may influence heat-related risk. As a result, residual confounding from unmeasured individual factors remains possible. Additional individual-level characteristics such as comorbidities, housing conditions, or access to AC, may also have influenced both heat exposure and EMS utilization and, therefore, resulted in confounding. By limiting the final analysis to lower socioeconomic status groups, variation in AC access is likely more comparable between UHI and non-UHI areas, as AC availability has previously been linked to socioeconomic status.47 In addition, age-stratified analyses help reduce potential confounding from comorbidities, which are strongly associated

Figure 5. Associated number of EMS encounters per 10,000 people by daily mean temperature, stratified by age group (panel arranged horizontally), sex, and weekday vs weekend (panels arranged vertically). Estimates are derived from a quasi-Poisson regression of EMS encounters in Rhode Island for June-August 2018-2021. Lines represent associated EMS use across a temperature gradient (55 °F to 95 °F), stratified by year (color), urban heat island (UHI) status (solid: UHI, dashed: non-UHI), and demographic subgroup. Across all strata, EMS demand increased with temperature, with consistently higher associated rates in UHI areas. Trends were more pronounced in older adults (≥ 65 years) and during weekdays. EMS, emergency medical services; UHI, urban heat island.

differences between the groups. Excluded encounters were younger, less likely to originate from UHIs, and had a higher proportion of males. Although these differences were statistically significant, they appear to be of limited clinical significance. The

Table 2. Rate ratio for the overall association of emergency medical services encounters with risk factors relative to the reference group (male, age < 65, non-urban heat island [UHI], weekday, 2020): by year, as well as combinations of year, sex/age group, and UHI exposure, associated with the rate ratios of daily EMS encounters for a fixed temperature. Estimates reflect combined main and interaction effects. Rate ratios for UHI are bolded. Male < 65

Male ≥ 65

Female < 65

Female ≥ 65

2018

2019

2020

2021

Weekday

Non-UHI

0.96 (0.89, 1.02)

0.90 (0.84, 0.96)

1.00

1.09 (1.02, 1.17)

Weekday

UHI

1.22 (1.15, 1.29)

1.20 (1.13, 1.28)

1.12 (1.06, 1.18)

1.23 (1.16, 1.31)

Weekend

Non-UHI

0.94 (0.87, 1.01)

0.88 (0.81, 0.95)

0.98 (0.95, 1.01)

1.07 (0.99, 1.15)

Weekend

UHI

1.19 (1.11, 1.28)

1.18 (1.10, 1.26)

1.10 (1.03, 1.17)

1.21 (1.12, 1.29)

Weekday

Non-UHI

3.50 (3.25, 3.78)

3.45 (3.20, 3.73)

3.50 (3.25, 3.78)

4.12 (3.83, 4.44)

Weekday

UHI

4.47 (4.16, 4.80)

4.64 (4.32, 4.99)

3.92 (3.61, 4.26)

4.65 (4.33, 4.99)

Weekend

Non-UHI

3.17 (2.93, 3.42)

3.12 (2.89, 3.38)

3.17 (2.97, 3.37)

3.73 (3.46, 4.02)

Weekend

UHI

4.03 (3.74, 4.34)

4.19 (3.89, 4.52)

3.54 (3.25, 3.86)

4.20 (3.90, 4.52)

Weekday

Non-UHI

1.03 (0.95, 1.10)

0.96 (0.89, 1.04)

1.07 (1.05, 1.10)

1.17 (1.09, 1.26)

Weekday

UHI

1.31 (1.22, 1.40)

1.29 (1.21, 1.38)

1.20 (1.13, 1.28)

1.32 (1.24, 1.41)

Weekend

Non-UHI

1.01 (0.93, 1.09)

0.94 (0.87, 1.02)

1.05 (1.01, 1.10)

1.15 (1.06, 1.24)

Weekend

UHI

1.28 (1.19, 1.38)

1.27 (1.17, 1.36)

1.18 (1.10, 1.26)

1.29 (1.20, 1.40)

Weekday

Non-UHI

3.76 (3.48, 4.07)

3.71 (3.43, 4.02)

3.76 (3.53, 4.02)

4.43 (4.11, 4.79)

Weekday

UHI

4.80 (4.45, 5.17)

4.99 (4.62, 5.38)

4.21 (3.86, 4.60)

5.00 (4.64, 5.38)

Weekend

Non-UHI

3.40 (3.14, 3.69)

3.35 (3.09, 3.64)

3.40 (3.18, 3.64)

4.00 (3.70, 4.33)

Weekend

UHI

4.33 (4.01, 4.68)

4.50 (4.17, 4.87)

3.80 (3.48, 4.16)

4.51 (4.18, 4.87)

UHI, urban heat island.

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with age. These unmeasured factors may have partially contributed to the observed associations; however, they are unlikely to fully explain the consistent patterns seen across years, temperature ranges, and demographic strata. In addition, this analysis only included EMS encounters linked to residential locations; therefore, certain at-risk populations were not captured in our cohort. These groups may include individuals experiencing homelessness, outdoor workers, and others who spend substantial time outside the home. Future research should specifically examine these populations to better understand their heat-related risks and EMS use patterns. Because Rhode Island has only one official weather station, we could apply only one daily average temperature measurement across the entire state. Temperature variations throughout the state are approximated each day by interpolated data products (e.g., DAYMET) and machinelearning models (e.g., XIS-Temperature).48-49 We plan to use these in future studies. Additionally, the assumed temperature variability of urban heat islands was calculated geographically based on historic time-averaged Landsat-8 data. Actual surface temperatures at the time of the encounter were not used, as raw surface temperature data were only available roughly once per 24 days.48 Other important weather attributes that potentially modulate heat exposure—humidity, direct solar radiation, precipitation, and wind—were also not captured. The EMS encounters were analyzed at the census block group level, UHI affect, and ADI levels based on the location of the EMS encounter. However, this location may not accurately reflect where they were exposed to heat, introducing potential misclassification. Limiting analyses to residential locations likely reduced misclassification from short-duration exposures in public or commercial venues (eg, parking lots, traffic accidents) and excluded large heat island zones that are typically air-conditioned, such as malls, airports, and office complexes. We defined UHI exposure using a 2019 and 2021 map and retrospectively applied it across corresponding study years (2018–2021). This assumes spatial stability in UHI intensity, which may not fully account for temporal changes in land use, vegetation, or surface reflectivity that could influence local heat patterns. Further, our findings may not be generalizable beyond Rhode Island given its unique geography, climate change profile, and urban design.

heat islands and non-urban heat island areas were measurable, reflecting unequal heat-related health impacts across communities. Targeted adaptations—such as enhancing local cooling infrastructure, improving heat-risk communication, and supporting high-risk neighborhoods with higher burdens of exposure to these heat islands—could help mitigate the disproportionate impacts of heat on vulnerable populations. AUTHORS CONTINUED Clara DiCerbo, PhD, CEM§ Hamid Torabzadeh|| Christopher H Schmid, PhD# Adam Aluisio, MD, MSc* Brown University, Department of Earth, Environmental, and Planetary Sciences, Providence, Rhode Island § Providence Emergency Management Agency, Providence, Rhode Island || Brown University, Division of Biology and Medicine, Providence, Rhode Island # Brown University School of Public Health, Department of Biostatistics, Providence, Rhode Island ‡

Address for Correspondence: Katelyn Moretti, MD, MS, Warren Alpert Medical School of Brown University, Department of Emergency Medicine, 55 Claverick St, Providence, RI 02903. Email: katelyn_moretti@brown.edu Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. Christopher H Schmid is partially supported by Institutional Development Award Number U54GM115677 from the National Institute of General Medical Sciences of the National Institutes of Health, which funds Advance Rhode Island Clinical and Translational Research (Advance RICTR). Support from the Biostatistics, Epidemiology and Research Design Core of Advance RI-CTR was received. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. Katelyn Moretti was funded through an internal grant provided by Brown Emergency Medicine. There are no conflicts of interest to declare. Copyright: © 2026 Moretti et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

CONCLUSION This study demonstrates that both elevated daily temperatures and exposure to an urban heat island are associated with increased EMS use during summer months in Rhode Island, specifically within residential areas that are both low socioeconomic status and urban heat islands. As climate change accelerates and extreme heat events become more frequent, EMS systems will continue to encounter temperature-related increases in demand. In this study, differences in EMS use between urban Western Journal of Emergency Medicine

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29. Browning MHEM, Rigolon A, Ogletree S, et al. The PAD-US-AR

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34. Gamble JL, Hurley BJ, Schultz PA, et al. Climate change and older

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44. Graham DA, Vanos JK, Kenny NA, Brown RD. Modeling the effects

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39. Whaley CM, Pera MF, Cantor J, et al. Changes in health services use

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among commercially insured US populations during the COVID-19

45. O’Neill MS, Carter R, Kish JK, et al. Preventing heat-related morbidity

pandemic. JAMA Netw Open. 2020;3(11):e2024984.

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40. Lasky E, Costello S, Ndovu A, et al. The health benefits of reducing

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46. Sera F, Hashizume M, Honda Y, et al. Air conditioning and heat-

temperature reduction on heat-related illnesses in California’s major

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47. Palinkas LA, Hurlburt MS, Fernandez C, et al. Vulnerable, resilient, or

heat island impacts on heat-related cardiovascular morbidity: a time

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42. Graham DA, Vanos JK, Kenny NA, Brown RD. Modeling the effects

48. Williams AA, Spengler JD, Catalano P, et al. Building vulnerability in a

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Scoping Review

Creating and Maintaining a “Climate-Smart” Emergency Department: A Scoping Review of Current Progress and Future Potential Lea Moujaes, MD Kayla Iuliucci, MD

Johns Hopkins University School of Medicine, Department of Emergency Medicine, Baltimore, Maryland

Section Editor: Mark I. Langdorf, MD, MPHE Submission history: Submitted September 25, 2025; Revision received December 27, 2025; Accepted January 2, 2026 Electronically published May 3, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.50597

Introduction: Climate change represents one of the most significant global health threats, with emergency departments (ED) serving as frontline responders to climate-related health emergencies. While EDs are major contributors to healthcare’s environmental footprint and critical responders for climate disasters, no comprehensive review has examined sustainability and climate-resilience initiatives specifically implemented in ED settings. Methods: We conducted a scoping review examining literature on sustainable and climate-resilient measures in EDs. Comprehensive searches of PubMed, Scopus, and Embase were performed from inception through November 2024, using terms related to EDs combined with sustainability and climate-resilience concepts. Two reviewers independently screened papers, with inclusion criteria requiring ED-specific focus and concrete sustainability or resilience interventions. Results: Seven studies met inclusion criteria, representing diverse geographic contexts. Three addressed sustainability interventions including waste reduction, sustainable procurement, device reprocessing, and renewable energy adoption. Case examples demonstrated co-benefits, such as 31% reduction in ambulance carbon dioxide emissions and $3 million savings from device reprocessing programs. All studies described resilience interventions encompassing disaster preparedness, surge capacity, infrastructure continuity, and clinical protocols. However, significant gaps were identified: Only 13-20% of hospitals in surveyed countries had disaster plans, and no studies documented fully operational climate-smart EDs. Global frameworks were referenced but not operationalized in ED settings. Conclusion: There is a limited body of peer-reviewed studies that describe measures to close the implementation gap between current climate science and operational practices in EDs. Despite extensive policy recommendations and demonstrated benefits, no studies have described any existing programs. Emergency medicine requires translation of conceptual frameworks into measurable interventions, standardized outcome measures, and systematic implementation of climate-smart healthcare practices. [West J Emerg Med. 2026;27(3)505–511.]

INTRODUCTION Climate change is increasingly recognized as one of the most prominent global health threats of the 21st century, with mounting evidence that its effects are already disrupting healthcare systems worldwide.1 Emergency departments (ED)

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are on the frontlines of this crisis, witnessing firsthand the consequences of rising global temperatures, extreme weather events, and deteriorating air and water quality. These climaterelated stressors are driving measurable increases in ED patient volumes, particularly during periods of extreme heat,

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The “Climate-Smart” ED: Scoping Review of Progress and Potential wildfires, flooding, and other climate disasters. Such events lead to spikes in heat illnesses, exacerbations of chronic diseases, trauma, and mental health emergencies disproportionately affecting vulnerable populations including the elderly, children, individuals with pre-existing health conditions, and communities that are socioeconomically disadvantaged.2 At the same time, the healthcare sector itself contributes significantly to the climate crisis, accounting for an estimated 4-5% of global greenhouse gas (GHG) emissions.3 In the United States, the healthcare industry has been estimated to contribute about 8.5-10% of the nation’s GHG emissions.4,5 In response to this paradox, health systems around the world have begun to implement mitigation and adaptation strategies aimed at reducing their environmental impact while preparing for climate-related disasters. These efforts include integrating the World Health Organization (WHO) framework for climate-resilient health systems, adopting renewable energy sources, decarbonizing supply chains, reforming wasteful procurement practices, and establishing institutional alliances committed to environmental sustainability. Several national health systems have also launched climate action plans, introduced emissions tracking metrics, and invested in greener infrastructure.6 Further, remarkable developments too recent to have been described in peer-reviewed literature have been initiated. Chief among these is the opening of an “allelectric” hospital that is fully renewably powered, at the University of California Irvine, in Irvine, CA.7And the British National Health Service (NHS) is systematically placing new, renewably powered ambulances into service, as current petroleum-powered ambulances are retired from service. This is but one component of Great Britain’s initiative to deliver a “net zero” NHS.8 Despite these promising developments, most sustainability initiatives remain focused at the hospital system level, with limited documentation of climateconscious interventions within specific clinical departments. Emergency departments, which operate around the clock and are among the most resourceintensive units in healthcare, have largely been left out of this conversation. Yet EDs are uniquely positioned to model both mitigation and adaptation strategies. Not only do they absorb the immediate impacts of climate-related health emergencies, but they also produce considerable waste, consume large amounts of energy (especially if the GHG emissions from ambulances that deliver patients to the ED are considered), and function as key decision-making nodes within hospitals. Given this dual role, EDs represent critical leverage points for climate action within the healthcare sector. However, to date there has been no comprehensive review of the strategies EDs have implemented to reduce their environmental footprint or to enhance their climate

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Moujaes et al. Population Health Research Capsule What do we already know about this issue? Climate change is increasing ED demand, and healthcare delivery contributes significantly to greenhouse gas emissions. What was the research question? What sustainability and climate-resilience interventions have been implemented in EDs? What was the major finding of the study? Only seven studies met criteria; no EDs reported fully implemented climate-smart programs. How does this improve population health? This scoping review reveals a persistent implementation gap, informing efforts to reduce ED emissions and strengthen preparedness for climate-related health threats.

resilience. A better understanding of these efforts is urgently needed to inform clinical operations, policy development, interdisciplinary collaboration, and emergency preparedness planning. We sought to address this gap by systematically identifying and analyzing the sustainability and climateresilience initiatives that have been implemented in EDs and described in peer-reviewed literature. Specifically, we aimed to map the range of environmental interventions described in the literature, assess the use of global climate- and disasterresilience frameworks in the ED setting, and highlight opportunities for future development, collaboration, and standardization in ED-based climate action. METHODS Study Design In this scoping review we examined the literature on implementation of sustainable and climate-resilient measures in the ED. We conducted comprehensive searches of three electronic databases: PubMed; Scopus; and Embase from inception through November 2024. Only English-language studies were included. The search strategy combined terms related to EDs (eg, “emergency department,” “emergency room,” “ED,” “ER”) with sustainability and climate resilience terms (eg, “sustainability,” “climate resilience,” “climate adaptation,” “environmental sustainability,” “green

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healthcare,” “carbon footprint”). We used Boolean operators to combine search terms appropriately. Study Selection and Screening We imported search results into Covidence software (Veritas Health Innovations, Ltd, Melbourne, Victoria, Australia) for screening and management, completed by December 2024. Two reviewers independently screened titles, abstracts, and full-text papers. We included studies that were specifically focused on EDs and addressed specific sustainability and resilience tactics or interventions. We excluded studies conducted outside ED settings or those that did not address concrete techniques for resilience and sustainability implementation. Initial screening yielded 217 papers for full-text review. Following application of inclusion and exclusion criteria, seven papers met criteria for final inclusion in the review.

renewable energy adoption.12,13 Case examples demonstrated potential for both environmental and financial co-benefits. For instance, a U.S. emergency medical services (EMS) fleet conversion achieved a 31% reduction in ambulance CO₂ emissions over one year, while single-use device reprocessing programs at one hospital saved $3 million and diverted nearly 19,000 pounds of waste in the same period.12 Health-sector recommendations emphasized the importance of energy audits, sustainable building standards, reducing petroleum dependence in EMS, and promoting carbon literacy among clinicians and administrators.12,13 At the policy level, international reviews highlighted the U.S. Department of Health and Human Services (HHS) sustainability plans and WHO calls for climate-smart, low-carbon healthcare facilities.9 Across these studies, no papers reported the existence of a fully climate-smart ED in practice, and no empirical data quantified reductions in ED-specific carbon footprints.9,12,13

Data Extraction Data extraction focusing on qualitative concepts was completed by February 2025 using dual review methodology. Given the exploratory nature of this scoping review, we did not employ strict systematic review protocols such as PRISMA guidelines. Data were extracted and compiled in Microsoft Excel (Microsoft Corporation, Redmond, WA) for analysis.

Climate Resilience Interventions All seven studies described resilience interventions relevant to EDs.9-15 Reported domains included disaster preparedness, surge capacity, infrastructure continuity, clinical protocols, and surveillance systems. Preparedness and surge planning were recurrent themes. In Tanzania, a national survey of 25 hospitals (2012) reported that only 20% had disaster plans, fewer than half had intensive care unit (ICU) capacity, and none met all surge capacity criteria. In Sri Lanka, a 2010 survey of 31 public health facilities found that only 13% had disaster plans. In Vietnam, a 2009 hospital survey indicated that more than 80% of health workers reported inadequate disaster training.10 Infrastructure vulnerabilities were noted across several contexts. Studies from Ghana and Nigeria described unstable electricity supply, inadequate drainage and sanitation, poor ventilation, and physical access barriers as key threats to continuity of care during climate-related events.14 Clinical tools and protocols were introduced in two studies. Nicholas et al developed a mnemonic tool—A CLIMATE (Act, Consider, Learn, Implement, Manage, Act, Treat, Evaluate/Educate)—to guide ED climate-related assessment and management, while Sorensen et al provided clinical practice recommendations for managing heat illness, respiratory disease, cardiovascular disease, and disasterrelated trauma.11 Surveillance and early warning systems were also highlighted. In the U.S., New York City’s syndromic surveillance system uses ED triage data to detect heat-related illness, while the Phoenix, AZ, forecast office of the National Weather Service issues pre-heat alerts to case managers and first responders.11 In Africa, the Global Rural-Urban Mapping Project (GRUMP) mapping was proposed as a tool to assess flood and landslide risks, and the WHO Strategic Tool for the Analysis of Risk (STAR) was recommended for structured disaster preparedness planning.11,13,14

RESULTS Study Selection and Characteristics Seven studies met the inclusion criteria and were included in the review.9–15 They represented a mix of systematic and scoping reviews, narrative and conceptual analyses, a primer introducing a framework for climate-smart EDs, a clinical-tool development paper, and an international policy perspective. Collectively, the studies spanned diverse geographic contexts, including the U.S.,11,13,15 low- and middle-income countries in multiple regions,10 a continent-wide review focused on Africa,14 and papers addressing international or cross-regional perspectives.9 The EDs were described broadly as critical, high-volume hospital entry points and frontline disasterresponse nodes.10,11,13,14 However, few studies reported specific ED size or volume data; most focused on system-level vulnerabilities, facility preparedness, or conceptual frameworks.9–11,13,14 Vulnerable populations that were consistently identified across studies included children, older adults, women and pregnant persons, people with chronic disease, and socially marginalized groups.9,11,13,14 Sustainability Interventions Three of the included studies addressed sustainability and mitigation strategies relevant to EDs.9,12,13 Reported operational domains encompassed waste segregation and reduction, sustainable procurement, device reprocessing, energy and water efficiency, green transportation, and

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persons, and socially marginalized populations that face disproportionate risks from climate-related events.9,11,13

Use of Frameworks A range of global, regional, and ED-specific frameworks were referenced across the included studies. Global health frameworks included the WHO climate-resilient health systems framework and the Sendai Framework for Disaster Risk Reduction,9,10,14 both cited in reviews of emergency care in low- and middle-income countries and African contexts. Regional and national tools included the HHS Sustainable and Climate-Resilient Healthcare Facilities Toolkit in the U.S., as well as municipal- and regional-level strategies such as the Accra Climate Action Plan in Ghana. Major sustainability initiatives are also underway within the British NHS. The NHS has launched a comprehensive decarbonization strategy, “Delivering a Net Zero National Health Service,”8 outlining a nationwide approach to reducing healthcare-related emissions. As part of this work, some regions have begun transitioning ambulance fleets to electric, zero-emission vehicles. In the Hillingdon region of suburban London, all patient-transport ambulances have been replaced with electric vehicles,16 and Yorkshire Ambulance Service has begun introducing electric ambulances as part of its broader sustainability plans.17 These developments represent emerging examples of health-system decarbonization efforts with implications for emergency and prehospital care. African studies also referenced WHO STAR, GRUMP, and broader adaptation measures in the United National Framework Convention on Climate Change adaptation measures.9,11,14 Less common are ED-specific frameworks.14 As referenced above, Nicholas et al introduced the A CLIMATE tool for use in the ED to guide clinical assessment and management of patients affected by climate-sensitive exposures.15 Across all studies, frameworks were described in relation to emergency medicine but were not reported as being fully operationalized within an ED.9–15

DISCUSSION This review represents, to our knowledge, the first synthesis of literature examining sustainability and climate resilience interventions relevant to EDs. Across seven included studies, we found increasing recognition of the ED’s dual role as a major contributor to health system environmental impacts and as a frontline responder to climaterelated health threats. While the literature describes a wide range of potential strategies, most reports remain conceptual, highlighting a persistent gap between frameworks and actual implementation in ED settings. Sustainability Interventions Evidence of environmental footprint reduction in EDs was largely limited to hospital- or EMS-level examples rather than department-specific programs. Reports of waste reduction, device reprocessing, and fleet emission reduction illustrate the feasibility of health-sector mitigation and demonstrate both environmental and financial co-benefits.12,13 However, no studies describe the existence of a “climate-smart” ED in practice nor do any describe data-quantified ED-specific carbon footprints.9,12,13 This gap is significant given the energy-intensive nature of emergency care and the growing imperative for health systems to reduce GHG emissions. For broader context, healthcare systems are responsible for 4-5% of global GHG emissions,18 with the U.S. health sector producing 8.5-10% of total U.S. emissions, reaching 1,692 kilograms per capita in 2018, the highest rate among industrialized nations.4,5 Moving forward, ED-level carbon accounting and evaluation of targeted sustainability interventions will be essential for translating conceptual recommendations into measurable practice.

Opportunities for Future Development The included studies identified several areas where future efforts could enhance ED sustainability and resilience. Research priorities were emphasized across the literature, particularly the need for more empirical studies evaluating ED-specific interventions. This gap was consistently noted as a barrier to advancing evidence-based practice in climate resilience and sustainability. Operational improvements included the development of standardized preparedness checklists and the implementation of simulation-based disaster training programs. Authors also recommended incorporating sustainability and resilience indicators into routine ED quality improvement processes.9,10,14 Systems integration was another recurrent theme, with calls for stronger partnerships between EDs, hospital operations, public health agencies, EMS, and community services to improve coordination and preparedness across the health systems.11,13,14 Equity considerations were consistently highlighted, with repeated recommendations to strengthen protections for children, older adults, pregnant

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Climate Resilience Interventions All included studies emphasized resilience, underscoring that EDs are critical nodes of health system preparedness and continuity during climate-related events. Findings consistently revealed deficits in hospital disaster planning and surge capacity, particularly in low- and middle-income countries. Rublee et al reported that only 20% of hospitals in Tanzania had disaster plans and fewer than half had ICU capacity, while in Sri Lanka only 13% of hospitals had disaster plans and most respondents lacked disaster training.10 In Vietnam, more than 80% of health workers had not received formal disaster preparedness education.10 Even in high-resource settings, infrastructure vulnerabilities such as unstable power supply, inadequate ventilation, and supply chain disruptions were highlighted as risks to ED continuity.11,13 Clinical preparedness tools, such as the mnemonic A CLIMATE15 and condition-specific care

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pathways,11 demonstrate early steps toward integrating climate considerations into everyday ED practice. Similarly, examples of syndromic surveillance in New York City and pre-heat alerts in Phoenix illustrate the potential of linking ED data with early-warning systems.11,13 Yet these efforts remain fragmented, and systematic evaluations of their effectiveness are lacking.

medicine is at an early but pivotal stage in dealing with climate change. Emergency departments have been described as experiencing “a large burden” from climate change through their focus on urgent and emergency care, their role as a safety net for vulnerable populations, and their leadership in disaster medicine.11 Yet the specialty has not yet translated this recognition into widespread operational change. As health systems pursue decarbonization goals and prepare for increasing climate shocks, EDs have a unique opportunity to serve as both test sites and exemplars of climate-smart care.12 This will require integrating environmental sustainability into departmental quality initiatives, adopting resilience metrics as part of preparedness processes, and ensuring that equity remains central to all climate and health strategies.

Framework Utilization The literature frequently cited global and national frameworks including the WHO climate-resilient health systems framework, the Sendai Framework for Disaster Risk Reduction, and the HHS Sustainable and Climate-Resilient Healthcare Facilities Toolkit as reference points for action.9–11,14 Municipal and regional planning tools, such as the Accra Climate Action Plan, were also described.14 Nicholas et al introduced the only ED-specific framework, A CLIMATE, as a tool to guide clinicians in integrating climate considerations into patient care. The acronym stands for “A— Act immediately to stabilize life- and limb-threatening conditions; C—Consider the climate-and-health etiology of symptoms; L—Learn from a climate health history; I— Implement a climate- and health-focused assessment; M— Manage the ongoing care of the climate-related emergency; A—Act to integrate an action plan that includes physiological and psychological climate symptoms; T—Treat urgent climate symptoms and consequences; and E—Evaluate, educate, and refer for long-term follow-up.”15 Across studies, frameworks were referenced but not reported as being fully operationalized within ED settings. For context, updated versions of these frameworks continue to emphasize health system decarbonization and resilience.19

LIMITATIONS This scoping review has several limitations. First, the number of eligible studies was small, and the evidence base remains limited in both scope and depth. Most included papers were conceptual or review-based rather than empirical, and only a few provided primary data from hospital preparedness surveys. Thus, our synthesis reflects proposed frameworks and recommendations more than evaluated interventions. Second, while we sought to capture ED-specific initiatives, much of the available literature reported on hospital- or EMS-level strategies, and no study provided quantitative data on ED-specific carbon footprints. Third, the included studies varied widely in geographic focus, methodology, and level of detail, which limited direct comparison across settings. Fourth, although we conducted a systematic search across major databases, relevant articles may have been missed, particularly those published in the gray literature or in languages other than English. Additionally, many of the included studies predated recent policy developments, such as the 2023 WHO Operational Framework for Climate-Resilient and Low-Carbon Health Systems and updated global frameworks from the HHS. Because many of the included studies were published more than five years ago, it is possible that additional ED-level sustainability and climate-smart interventions have been implemented more recently but have not yet appeared in the peer-reviewed literature. The existence of these newer frameworks suggests that efforts to reduce the GHG impact of ED operations may already be underway but remain unreported. Although this review primarily focused on peer-reviewed evidence, emerging national-scale sustainability efforts, such as those currently being implemented within the British NHS, including the introduction of electrically powered, renewably powered ambulances, indicate that system-wide changes in emergency and prehospital care are ongoing but incompletely captured in published research. These developments also highlight differences in healthsystem organization across countries. In the United Kingdom, the NHS operates a unified national EMS system, which may

Opportunities for Development Several recurring themes emerged across studies as opportunities for advancing ED sustainability and resilience. Research priorities include the need for empirical studies that evaluate ED-specific interventions, as the current evidence base is dominated by conceptual and review papers.10,13-15 Operational recommendations emphasize standardized preparedness checklists, simulation-based disaster training, and the incorporation of sustainability and resilience indicators into ED quality improvement processes.9,10,14 Systems-level integration was identified as crucial, with calls for closer collaboration between EDs, hospital operations, public health, EMS, and community services.11,13,14 Finally, equity considerations were consistently highlighted, with recognition that children, older adults, pregnant persons, and socially marginalized groups face disproportionate risks during climate-related.9,11,13,14 Implications for Emergency Medicine The findings of this review suggest that emergency

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Moujaes et al.

facilitate large-scale transitions to low-emission emergency transport. In contrast, the fragmented and locally governed EMS structure in the U.S. may pose barriers to similar implementation efforts. Additionally, because more recent initiatives may not yet be published, the true extent of current ED sustainability and resilience practices may be underestimated. These limitations highlight the need for more empirical research on ED-specific interventions and the development of standardized outcome measures to guide climate-smart healthcare initiatives.

The time for conceptual discussion has passed. Emergency departments must now move beyond frameworks to become active implementers of climate-smart healthcare practices. This shift from theory to practice is critical for addressing both patient health outcomes and environmental impact.

CONCLUSION This scoping review represents one of the first examinations of sustainability and climate resilience initiatives specific to EDs. Our findings reveal a striking paradox: While EDs are both major contributors to healthcare’s environmental footprint and frontline responders to climate-related health threats, there exists a profound gap between conceptual frameworks and operational implementation. Despite recommendations from global health organizations and the existence of multiple climate-resilience frameworks, we identified no studies documenting fully implemented climatesmart EDs. This is particularly concerning given that healthcare systems contribute 4-5% of global greenhouse gas emissions, with emergency care representing one of the most resource-intensive components of hospital operations. In the U.S., this impact is more pronounced, with healthcare responsible for an estimated 8.5-10% of national greenhouse gas emissions. far exceeding the global average and underscoring the urgency for EDs to adopt and operationalize mitigation strategies. The literature consistently describes what EDs should do to address climate change but provides no evidence of what they are doing. The climate and health crisis demands immediate action from the specialty of emergency medicine. Emergency departments occupy a unique position as both environmental contributors and essential responders in climate disaster response. This represents an opportunity for emergency medicine to lead healthcare’s climate response while improving patient outcomes and reducing operational costs. The co-benefits documented in hospital-level interventions— such as the 31% reduction in ambulance CO₂ emissions and $3 million savings from device reprocessing programs— suggest significant potential returns on investment. Emergency medicine now stands at a pivotal moment. The frameworks exist, the urgency is clear, and the opportunity for impact is large. What is needed is the translation of recommendations into practice through research, standardized outcome measures, and systematic implementation of EDspecific interventions. Future efforts must focus on evaluation of sustainability initiatives, development of climate-resilience metrics, and integration of equity considerations into all climate and health strategies.

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Address for Correspondence: Lea Moujaes, MD, Johns Hopkins University School of Medicine, Department of Emergency Medicine, 1830 E Monument Street, Baltimore, Maryland 21205. Email: lmoujae1@jhmi.edu.

Copyright: © 2026 Moujaes et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES 1. World Health Organization. Climate change. 2023. Available at: https://www.who.int/news-room/fact-sheets/detail/climate-changeand-health. Accessed September 23, 2025. 2. Chung JW, Meltzer DO. Estimate of the carbon footprint of the US health care sector. JAMA. 2009;302(18):1970-2. 3. Josh Karliner, Scott Slotterback, Richard Boyd, et al. Health care without harm. Health care’s climate footprint: how the health sector contributes to the global climate crisis and opportunities for action. 2019. Available at: https://www.commonwealthfund.org/publications/ explainer/2022/apr/how-us-health-care-system-contributes-climatechangehttps://global.noharm.org/sites/default/files/documentsfiles/5961/HealthCaresClimateFootprint_092319.pdf. Accessed May 10, 2025. 4. The Commonwealth Fund. How the U.S. health care system contributes to climate change. 2022. Available at: https://www.commonwealthfund. org/publications/explainer/2022/apr/how-us-health-care-systemcontributes-climate-change. Accessed November 12, 2025. 5. Eckelman MJ, Huang K, Lagasse R, et al. Health care pollution and public health damage in the United States: an update. Health Aff (Millwood). 2020;39(12):2071-9. 6. World Health Organization. Operational framework for building climate resilient health systems. 2015. Available at: https://www.who. int/publications/i/item/operational-framework-for-building-climateresilient-health-systems. Accessed September 23, 2025. 7. UCI Health. UCI Health making history with nation’s first all-electric acute care hospital. 2025. Available at: https://www.ucihealth.org/about-us/ news/2025/06/all-electric-hospital. Accessed November 20, 2025.

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8. NHS England. Delivering a “Net Zero” National Health Service. 2022.

14. Theron E, Bills CB, Calvello Hynes EJ, et al. Climate change and

Available at: https://www.england.nhs.uk/greenernhs/wp-content/

emergency care in Africa: a scoping review. Afr J Emerg Med.

uploads/sites/51/2020/10/delivering-a-net-zero-national-health-

2022;12(2):121-8.

service.pdf. Accessed November 12, 2025.

15. Nicholas PK, Breakey S, McKinnon S, et al. A CLIMATE: a tool for

9. Ghazali DA, Guericolas M, Thys F, et al. Climate change impacts on

assessment of climate change-related health consequences in the

disaster and emergency medicine focusing on mitigation disruptive

emergency department. J Emerg Nurs. 2021;47(4):532-42.e1.

effects: an international perspective. Int J Environ Res Public Health.

16. Hillingdon Hospitals NHS Foundation Trust. UK first as all patient

2018;15(7):1379.

ambulances go electric. 2025. Available at: https://thh.nhs.uk/

10. Rublee C, Bills C, Sorensen C, et al. At ground zero—emergency

news-events/uk-first-as-all-patient-ambulances-go-electric-2403/.

units in low- and middle-income countries building resilience for

Accessed November 20, 2025.

climate change and human health. World Med Health Policy.

17. BBC News. Electric ambulances trialled in North Yorkshire. 2025.

2021;13(1):36-68.

Available at: https://www.bbc.com/news/articles/c2emywnpeg2o.

11. Sorensen CJ, Salas RN, Rublee C, et al. Clinical implications of

Accessed November 20, 2025.

climate change on US emergency medicine: challenges and

18. Rodríguez-Jiménez L, Romero-Martín M, Spruell T, et al. The carbon

opportunities. Ann Emerg Med. 2020;76(2):168-78.

footprint of healthcare settings: a systematic review. J Adv Nurs.

12. Linstadt H, Collins A, Slutzman JE, et al. The climate-smart

2023;79(8):2830-44.

emergency department: a primer. Ann Emerg Med.

19. World Health Organization. WHO unveils framework for climate

2020;76(2):155-67.

resilient and low carbon health systems. 2023. Available at: https://

13. Hess JJ, Heilpern KL, Davis TE, et al. Climate change and

www.who.int/news/item/09-11-2023-who-unveils-framework-for-

emergency medicine: impacts and opportunities. Acad Emerg Med.

climate-resilient-and-low-carbon-health-systems. Accessed

2009;16(8):782-94.

September 23, 2025.

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Brief Educational Advances

Implementing a Climate Health Education Curriculum for Emergency Medicine Trainees and Faculty Eric Lewis, DO* Courtney M. Smalley, MD† Matthew Kostura, MD†

*The MetroHealth System, Cleveland, Ohio † Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland Clinic Health System, Department of Emergency Medicine, Cleveland, Ohio

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted September 2, 2025; Revision received December 21, 2025; Accepted January 2, 2026 Electronically published May 3, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.50824

As climate-related health impacts intensify, emergency physicians (EP) increasingly encounter patients whose conditions are influenced by environmental change. To provide care for climatevulnerable patients in the emergency department (ED), EPs should be educated on the impacts of climate change. The goal of our intervention was to provide a structured climate health educational curriculum to attending physicians, residents, and medical students and assess the perceived effectiveness of the curriculum. A longitudinal climate health curriculum was delivered in a fourpart lecture series over the course of three months to medical students, postgraduate year 1-3 emergency medicine residents, and academic emergency attending physicians. We measured learners’ perceived knowledge pre- and post-curriculum with surveys assessing four core areas: 1) climate change topics; 2) climate impacts on human health; 3) confidence in treating medical conditions exacerbated by climate change; and 4) climate change solutions. At the completion of the three-month curriculum, the learners reported a statistically significant improvement in perceived level of knowledge in overall climate health topics in 87.5% (28/32 concepts with P < .05) of concepts assessed during the climate health education curriculum. Specifically, learners reported a perceived knowledge improvement in concepts of general climate change (6/6 topics, P < .05), impacts on human health (7/8 topics, P < .05), confidence in treating medical conditions exacerbated by climate change (8/9 topics, P < .05), and knowledge of climate solutions (7/9 topics, P < .05). Overall, learners reported a higher median likelihood of implementing individual climate solutions after the conclusion of the climate health education curriculum, although this was not statistically significant (5.0 vs 7.0, P = .073). Our model introduces the concept of a longitudinal, lecture-based climate change curriculum to assist in educating resident learners in evidence-based climate health knowledge, assist in preparing EPs to better treat climate-vulnerable patient populations, and share climate solutions. [West J Emerg Med. 2026;27(6.1)98–102.]

INTRODUCTION The United Nations Intergovernmental Panel on Climate Change Sixth Assessment Report established that the average global surface temperature of the Earth between 2011–2020 has risen by 1.09 °C since the pre-industrial period (1850–1900) and correlated with increases in the atmospheric concentration of carbon dioxide.1 There is compelling evidence that global surface temperature rise has been primarily caused by humandriven greenhouse gas (GHG) emissions.1 Western Journal of Emergency Medicine

Multiple studies have evaluated the impact of climate change on the medical field and vulnerable patient populations.2-6 The World Health Organization conservatively projected that by the 2030s an additional 250,000 deaths per year globally would be associated with climate change impacts.7 As climate-related health impacts intensify, emergency physicians (EP) will increasingly encounter patients whose conditions are influenced by environmental change. Recent literature has further looked at how the climate 98

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health changes will specifically affect emergency medicine (EM).2,8,9 Patients affected by heatwaves, flooding, weather disasters, cardiopulmonary illness exacerbated by poor air quality, and the expansion of vector-borne infectious diseases will seek care in the emergency department (ED).2 Therefore, EPs need to be educated on the impacts of climate change to be prepared to treat these patients.2,6,8,9 However, the literature is sparse on the implementation of a climate health curriculum in EM residency training.10,11

Additionally, the session introduced eight broad ways climate change is impacting human health.5 The initial lecture introduced the following climate topics: severe weather; air pollution; changes in disease vectors; increasing allergens; water quality; food and water supply impacts; environmental degradation; and extreme heat.3,5 Each subsequent didactic session was structured into three parts: deep dive into a climate change concept; teaching EM residency core curriculum (as per the guidelines of the Council of Residency Directors in Emergency Medicine)15 covering pathology exacerbated by climate change, and discussion of actionable climate change solutions to minimize GHG emissions (Figure 1). To measure the effectiveness and learners’ perceived knowledge gained from the curriculum, survey data were collected at multiple points throughout the three-month period. Surveys were electronic, conducted anonymously via an email link or a QR code, completed voluntarily, and were accessible immediately after each didactic session was completed. Learners initially completed a pre-curriculum survey that was emailed out one week prior to the initial didactic session and available via QR code immediately prior to the first session. This survey assessed baseline knowledge of concepts to be covered in the curriculum. Post-curriculum surveys were distributed to the learners who attended each lecture immediately after the lecture and via email available for completion up to one week post lecture. We initially intended to have one survey per lecture, but since lectures 1 and 2 were presented in the same didactic session, questions were combined into one survey that was sent out after lecture 2. These surveys included the same questions as the pre-curriculum survey, but only on topics specific to what had been taught thus far. For all surveys, learners were asked to rate responses on a 10-point Likert scale with 1 indicating “no confidence / no knowledge” and 10 indicating “very confident / very knowledgeable.” We assessed responses to the pre- and post-curriculum surveys using descriptive statistics and compared them using a MannWhitney U test to determine whether there was a change in median perceived knowledge or confidence level. A statistically significant change was defined as a P value ≤.05. Statistical analysis was performed using SAS v9.4 (SAS Institute Inc, Cary, NC). The primary outcome used to assess effectiveness of the curriculum was a statistically significant improvement in the median perceived knowledge level of individual climatechange concepts before and after delivery of each section of the climate health curriculum. Secondary outcomes included assessment of learners’ belief in human-driven climate change, likelihood of performing individual action to combat climate change, and an open comments section.

OBJECTIVES The purpose of our curricular intervention was to provide structured climate health education to EPs, EM residents, and medical students and to assess its effectiveness. Using a longitudinal lecture-based curriculum, we aimed to educate learners on climate health topics, discuss selected proposed climate solutions to ameliorate effects of climate change, and assess learners’ perceived understanding of the impacts of climate change on patient health in the ED. Physicians should understand both how to treat climate-vulnerable patients and the underlying global mechanisms by which their medical conditions are worsened. We aimed to prepare EPs for climate-related health emergencies and inspire them to support climate solutions.12 CURRICULAR DESIGN A longitudinal, climate-change educational curriculum was delivered in a four-part lecture series by an emergency attending physician or senior EM resident over three months during weekly EM resident didactic sessions in a three-year residency program. Our audience consisted of postgraduate year 1-3 EM residents, third- and fourth-year medical students who were on a one-month EM rotation, and academic emergency attending physicians. At this institution all participants receive an email describing the content of upcoming didactic sessions one week prior to the session; this also occurred during the months when the climate change curriculum was delivered. There was no additional formal recruitment of participants to the didactic sessions. While many participants likely attended more than one session, we did not track individual attendance. The overall goal of the curriculum was to deliver educational content on climate-sensitive diseases that impact EM. While the scope of climate change and impact on health is broad, the focus was to introduce general climate-change concepts and tie those concepts to medical conditions encountered in the ED. The didactic presentations were modeled on evidence-based approaches to teaching learners with the goal of presenting scientific data in an objective manner, including discussing limitations of the available studies. Didactic session #1 included an overview of foundational climate-change concepts and the impacts to the United States as outlined by the Fifth National Climate Assessment conducted by the National Oceanic and Atmospheric Administration.13

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IMPACT AND EFFECTIVENESS Nineteen learners completed the pre-curriculum survey.

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Lewis et al. Table 1. Total number of respondents to survey regarding a climate-change curriculum by level of education.

Figure 1. Overview and breakdown of topics covered in the four lectures of a climate health education curriculum. EM, emergency medicine; ECG, electrocardiogram; GI, gastrointestinal.

The three post-lecture surveys had a wide range of respondents from 7-27, which limited our analysis (Table 1). Overall, the majority of the respondents were EM residents (72.9%). Other respondents included medical students (20.3%) and attending physicians (6.8%). Table 1 shows the breakdown of respondents for each survey. In the pre-curriculum survey, 73.7% of respondents reported that they had never attended a lecture on climate change and its effect on human health. Climate change is not generally part of core medical school or graduate medical education curriculum.11,14 Therefore, the pre-curriculum survey provided valuable feedback demonstrating that many learners are not formally educated on this topic. When assessing individual topics that were presented, learners reported improved perceived knowledge or confidence in 87.5% of concepts (28/32 concepts with P < .05) that were assessed during the climate health educational curriculum (Figure 2). When assessing the four core areas of the curriculum individually—1) climate change topics, 2) climate impacts on human health, 3) confidence in treating medical conditions exacerbated by climate change, and 4) climate change solutions—the survey demonstrated improvement perceived knowledge in all four areas. Specifically, when evaluating perceived knowledge of the six core climate-change topics, every area showed statistically significant improvement in perceived knowledge (P < .05), demonstrating in our small cohort of learners that an introduction to climate change in a residency-based educational curriculum could have a large impact on climate change knowledge for future physicians. In the additional core topic areas, there was a reported increase in perceived knowledge level in 7 of 8 ways that climate change impacts human health (Figure 2). Learners also reported statistically significant improved confidence in treating 8 of 9 medical conditions exacerbated by climate change (Figure 2). Lastly, learners demonstrated statistically significant improved perceived knowledge of 8 of 10 climate change solutions (Figure 2). In the last question on the survey regarding

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ability to perform climate-change solutions, learners reported that they were more likely to perform individual climate solutions in the following six months after the conclusion of the climate health educational curriculum; however, this difference was not statistically significant and was limited by the low number of survey respondents to the final survey (5.0 vs 7.0, P = .073). In the open comments sections, learners stated that they had gained knowledge on the compounding effect of climate change on health, impacts of food waste, better management of gastrointestinal illness and meningitis, and various environmental impacts on different pathologies. Encouragingly, even before completion of the curriculum, 48.1% of respondents stated that they had implemented climate solutions including carpooling, composting, wasting less food, changing diet, conserving energy, and changing home energy suppliers to renewable resources. A limitation of this pilot curricular study is the small study size limited to one academic center focused on EM resident education. The varied number of survey responses, from 7-27 respondents, limits the power of our statistical analysis and any definitive conclusions as to the curriculum’s effectiveness. It is suspected that the low response rate to the final survey was due to the lecture being scheduled as the last of one of the didactic sessions, which extended into lunch break. Despite follow-up emails, the survey response rate remained low. Timing of the lectures within the didactic session is something to consider for future curriculum building. Additionally, since learners were self-reporting a perceived knowledge benefit and we did not perform a knowledge assessment, we are unable to comment on long-term retention. Finally, responses were analyzed as a whole and not broken down by level of education due to the small sample size. One would expect that a change in perceived knowledge level at baseline would differ between a medical student and an attending physician. Regardless of these limitations, the goal of the project was to introduce a curriculum to EM residents that had not been presented to them previously and was likely an area of reduced knowledge across residency programs, based on literature review.11,14 This project demonstrates that a simple, lecturebased curriculum introducing climate-related health concepts

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Figure 2. Comparison of participants’ median responses on a 10-point Likert scale between pre- and post-curriculum surveys in which they assessed a climate-related health curriculum.

can raise awareness of general climate issues, including how climate change is likely to impact ED patients. Future studies should assess knowledge retention and integration over the span of EM residency and could improve on our design to align with published, public- health core climate and health competencies such as those proposed by the Global Consortium on Climate and Health Education, as our curricular design was not based on published climate health competencies.16 CONCLUSION It is pivotal that current and future emergency physicians be aware of climate change and its effects on human health and be trained to treat climate-vulnerable patients, as well as to understand how to become advocates for climate change solutions. Our longitudinal curriculum improved learners’ overall perceived understanding and knowledge of climate change, its impact on patient health, and treating medical

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conditions exacerbated by climate change. After attending the course, learners reported that they were more likely to implement climate change solutions into their personal lives or had already implemented them. Although there are limitations to survey studies, we are encouraged by the positive results of our curriculum design and analysis. This intervention demonstrates one way to integrate climate health knowledge into the core EM residency curriculum. We encourage EM residencies to use this model and build on it to disseminate evidence-based, climate health knowledge to prepare physicians to treat climate-vulnerable patient populations and share climate solutions. ACKNOWLEDGMENTS We would like to thank Lu Wang, PhD, of the Cleveland Clinic Department of Quantitative Health Sciences for her contributions to the biostatistics.

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Lewis et al. Assessment. U.S. Global Change Research Program; 2016.

Address for Correspondence: Matthew Kostura MD, Cleveland Clinic Foundation, Department of Emergency Medicine, 9500 Euclid Ave, E19, Cleveland, OH 44195. Email: kosturm@ccf.org.

6. Crowley RA. Climate change and health: a position paper of the American College of Physicians. Ann Intern Med. 2016;164(9):608-10. 7. World Health Organization. Climate Change. 2023. Available at:

https://www.who.int/news-room/fact-sheets/detail/climate-changeand-health. Accessed June 5, 2025. 8. Hess JJ, Heilpern KL, Davis TE, et al. Climate change and emergency medicine: impacts and opportunities. Acad Emerg Med. 2009;16(8):782-94.

Copyright: © 2026 Lewis et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

9. Salas RN, Slutzman JE, Sorensen C, et al. Climate change and health: an urgent call to academic emergency medicine. Acad Emerg Med. 2019;26(7):837-40. 10. Philipsborn RP, Sheffield P, White A, et al. Climate change and the practice of medicine: essentials for resident education. Acad Med. 2021;96(3):355-67.

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1. Arias PA, Bellouin N, Coppola E, et al. Technical summary. In: Climate

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Panel on Climate Change. Cambridge University Press; 2021:33-144.

Lancet countdown on health and climate change. Lancet.

2. Sorensen CJ, Salas R, Rublee C, et al. Clinical implications of climate change on US emergency medicine: challenges and

2023;402(10419):2346-94. 13. Crimmins AR, Avery CW, Easterling DR, et al. Fifth National Climate

opportunities. Ann Emerg Med. 2020;76(2):168-78. 3. Pacheco SE, Guidos-Fogelbach G, Annesi-Maesano I, et al. Climate

Assessment. U.S. Global Change Research Program; 2023. 14. Wellbery C, Sheffield P, Timmireddy K, et al. It’s time for medical

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curriculum. Accessed August 29, 2025. 16. Sorensen C, Campbell H, Depoux A, et al. Core competencies to

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prepare health professionals to respond to the climate crisis. PLOS Clim. 2023;2(6):e0000230.

Change on Human Health in the United States: A Scientific

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Brief Research Report

Reducing Waste: Instrument Recycling in the Emergency Department Esther H. Chen, MD*† Kristie Taguma, MD‡ Newton Addo, MS* John K. Quinn, MD§

*University of California, San Francisco, Department of Emergency Medicine, San Francisco, California † Zuckerberg San Francisco General Hospital, San Francisco, California ‡ Kaiser Foundation Hospital-San Leandro, Department of Emergency Medicine, San Francisco, California § University of Washington, Department of Emergency Medicine, Seattle, Washington

Section Editor: Shahram Lotfipour, MD, MPH Submission history: Submitted September 20, 2025; Revision received January 4, 2026; Accepted January 21, 2026 Electronically published May 13, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.52924

Introduction: Emergency medicine (EM) residency programs are required to teach quality improvement (QI), yet few adopt a sustainability lens to QI despite broad recognition of the importance of climate sustainability in healthcare. To address this gap, some programs have piloted innovative approaches such as sustainability QI electives or projects, although evidence of their effectiveness remains limited. Methods: We designed and implemented a sustainability QI initiative to recycle used instruments from three bedside procedure kits (laceration repair, incision and drainage, chest tube placement) commonly used in the emergency department to reduce waste. Our goal was to describe the effectiveness of a financial intervention on instrument recycling by comparing the differences in recycling rates between the baseline and incentive periods using a quasi-Poisson regression analysis. Results: At the end of the first year of instrument recycling, the recycling rate was 9%. Providing a financial incentive to residents over a two-year period significantly increased the recycling rate to a mean of 24% (standard deviation 13), with a rate ratio of 3.03 (95% CI 1.57–5.85), P < .001. While the residents did not meet their recycling target of 50% to receive the incentive payment, their overall recycling rate increased. Conclusion: Providing a financial incentive to residents for recycling efforts was modestly successful in encouraging residents to participate in an instrument recycling initiative. Motivating busy clinicians to engage in sustainable practice is challenging; projects that prioritize systems-level changes may be more effective than those that require changes in individual clinical practices. [West J Emerg Med. 2026;27(6.1)103–106.]

INTRODUCTION Emergency medicine (EM) residency programs are required to teach quality improvement (QI) concepts, preparing residents to identify opportunities to enhance clinical practice through streamlined processes and improved patient safety.1,2 However, few programs approach QI using the lens of climate sustainability or incorporate sustainable QI and climate change and health (CCH) topics into their core curricula.3 One program implemented a climate health elective rotation in which EM Volume 27, Supplement: November 2026

residents learn sustainable clinical practice principles and apply those principles to design and implement a sustainability QI capstone project.4 While promising, curricular interventions have been found to be least effective in promoting sustainable behavior change, whereas social comparisons or financial incentives were the most effective.5 Recognizing a curricular gap in our own program, we implemented an instrument recycling sustainability QI initiative to teach residents about reducing waste generated 103

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Reducing Waste: Instrument Recycling in the Emergency Department during routine clinical practice. Emergency departments (ED) contribute to greenhouse gas emissions by generating a significant amount of waste, deviating from hospital waste disposal policies (ie, throwing waste in regulated waste red bags), or mixing waste with recyclable paper or plastics.6 Waste reduction strategies such as increased recycling and reprocessing of single-use devices may reduce carbon dioxide emissions and lead to financial cost-savings.7 Clinician-level strategies to reduce waste-related emissions include recycling of single-use materials and reducing the disposal of unused equipment.8 Our ED had already been collecting unused supplies from procedure kits for resident teaching and international distribution.9 To further reduce clinician-generated waste, we decided to implement recycling of instruments from procedure kits used during clinical care. We describe our experience with providing a financial incentive to increase instrument recycling in a busy ED setting, aiming to teach residents to approach sustainability QI with the same rigor as patientfocused QI projects. METHODS Setting and Participants The EM residency program has 60 postgraduate year 1-4 residents who spend about 50% of their clinical time at the county hospital and trauma center ED (annual census about 65,000 patients). This project was approved as exempt from institutional review. Design In June 2022, the county hospital implemented recyclable instruments in the commonly used bedside procedure kits (ie, laceration repair, incision and drainage, chest tube placement). Rather than disposing instruments into the room’s sharps container, instruments could be deposited into a recycling bin in the soiled utility room located in each clinical area. Instruments were collected and recycled by the instrument manufacturer when the bins were completely full. The hospital incurred no additional cost for instrument recycling. This recycling initiative was announced in July 2022 to faculty at faculty meeting and to residents during residency conference. In July 2023, we proposed that the instrument recycling project be part of the hospital’s pay-for-performance (P4P) program for QI and sustainability QI initiatives. This pay-forperformance program has been successful in engaging trainees to participate in QI efforts for a financial incentive.10 The instrument recycling project was approved for the 2023-2025 academic years, in which all EM residents would receive $400 at the end of the year for meeting their monthly instrument recycling goal for at least six months of the academic year. Outcome Measurements and Analysis Our primary outcome was the monthly recycling rate. To

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Population Health Research Capsule What do we already know about this issue? Financial incentives may be more effective than curricular interventions to promote sustainable, clinician-level behavior change. What was the research question? We tested the effectiveness of offering a financial incentive to residents to increase instrument recycling. What was the major finding of the study? Instrument recycling increased from 9% to 24%, with a rate ratio of 3.03 (95% CI 1.57–5.85), P < .001. How does this improve population health? Financial incentives could promote sustainable clinical practice and reduce waste-related emissions.

establish a baseline, we measured the weight of recycled instruments in July 2023 using the ED standing scale and continued monthly measurements during the first week of each month. We calculated the per-unit weight by weighing the recyclable instruments of each kit. Every month, we calculated the expected weight of recycled instruments by multiplying the per-unit weight by the number of kits replaced from the hospital’s central supply (assuming 100% of the instruments were recycled). We defined the recycling rate as the actual weight of recycled instruments divided by the expected weight of the instruments from the replaced kits. Additionally, from July 2024–June 2025, we recorded the monthly number of laceration repair, incision and drainage, and chest tube placement procedure notes documented in the electronic health record to provide another estimate of the total weight of used kits. Data are presented using descriptive statistics with means and standard deviations as appropriate. We used a generalized linear model with a quasi-Poisson distribution, month of observation, and a log-link function to assess the differences in recycling rates between the baseline and incentive periods. We report rate ratios (RR) and 95% confidence intervals, with the baseline period serving as the reference group. All analyses were performed with R v4.4 (The R Foundation for Statistical Computing, Vienna, Austria).

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Reducing Waste: Instrument Recycling in the Emergency Department

RESULTS At the end of the first year of instrument recycling (July 2022–July 2023), the recycling rate was 9%. Providing a financial incentive to residents from July 2023–June 2025 significantly increased the recycling rate to a mean of 24% (SD 13), with a RR of 3.03 (95% CI 1.57–5.85), P < .001. The monthly instrument recycling rate (Figure) and weight of recycled instruments were variable (Table). The residents did not meet their recycling target of 50% of instruments recycled over the two-year period and, therefore, did not receive an annual $400 incentive payment.

Table. Monthly recycling rate and weight of recycled instruments in the emergency department.

DISCUSSION Our sustainability QI project was successful in increasing the overall instrument recycling rate in the ED although there was month-to-month variability. Despite not reaching the proposed recycling target of 50%, the overall instrument recycling rate increased from 9% to 24%. and a sustained improvement was observed in the project’s second year. We concurrently implemented a climate change and health curriculum into weekly conferences, using these sessions to provide quarterly reminders to residents about the instrument recycling program as a way to reduce environmental waste. In addition, resident QI leaders highlighted the program with reminders during shift handoffs and provided orientation on the recycling workflow to non-EM rotators and medical students. However, this project also highlighted the challenge of implementing a sustainability QI project that depended on changing individual behavior in a busy clinical environment

kg, kilogram.

Figure. Monthly instrument recycling rate with the timeline of the climate lecture series. SusQI, sustainability quality improvement.

and the cognitive load of adopting a new process. The recycling workflow required already busy residents to collect and transport their instruments to the soiled utility room rather than simply depositing them directly into the sharps containers located in each patient room. Residents rotate to different clinical sites every 2–4 weeks, which can potentially lead to confusion regarding which QI and sustainability QI initiatives were implemented at each location. Faculty may also be unable to consistently remind residents about instrument recycling when supervising procedures, particularly if they are not present during cleanup. Additionally, more than 50% of resident shifts are staffed by non-EM residents, who may be unaware of recycling efforts. Finally, residents face competing priorities, such as optimizing patient care, which may overshadow any consideration of sustainable clinical practices. While not meeting the recycling goal was disappointing, this project showed that sustainability QI initiatives targeting system-level change rather than focusing on changing practice

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Date

105

Recycling rate (%)

Weight (kg)

Jul 2023

21 (total weight from 7/22-7/23)

Aug 2023

Sep 2023

2.5

Oct 2023

1.5

Nov 2023

1.9

Dec 2023

2.9

Jan 2024

5.9

Feb 2024

2.6

Mar 2024

1.7

Apr 2024

3.7

May 2024

3.3

Jun 2024

Jul 2024

3.9

Aug 2024

2.5

Sep 2024

2.7

Oct 2024

3.1

Nov 2024

3.9

Dec 2024

2.5

Jan 2025

4.4

Feb 2025

3.1

Mar 2025

Apr 2025

May 2025

Jun 2025

3.1

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Reducing Waste: Instrument Recycling in the Emergency Department at an individual level may be more effective in achieving desired outcomes. For example, a prior ED sustainability QI initiative implemented automatic double-sided printing of after-visit summaries by adjusting the default settings of all departmental printers. This system-wide change eliminated the need to modify settings manually and effectively reduced paper use by preventing single-sided printing. For the instrument recycling initiative, even though financial incentives improved the recycling rate, we might have seen greater success if we had been able to simplify the instrument disposal workflow by installing recycling bins in each patient room. Alternatively, EDs could take steps to more fully integrate climate sustainability into their culture and expand their clinicians’ knowledge of sustainable practices with consistent communication about sustainability QI initiatives, in the same way as patient-focused QI initiatives.

Address for Correspondence: Esther H. Chen, MD, Zuckerberg San Francisco General Hospital, 1001 Potrero Ave, San Francisco, CA 94110. Email: esther.chen@ucsf.edu Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Chen et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/ REFERENCES 1. Beeson MS, Bhat R, Broder JS, et al. The 2022 Model of the Clinical Practice of Emergency Medicine. J Emerg Med. 2023;64(6):659-95.

LIMITATIONS This project had several limitations. It was conducted with a single residency program at an institution that benefits from a pay-to-perform improvement program and dedicated QI faculty mentorship, which may limit generalizability to other settings. In addition, we encountered specific hospital system challenges during our study period, which limited our interventions (ie, installing recycling bins in each patient room). Furthermore, we implemented a concurrent quarterly climate change and health lecture series during residency conference to teach residents to manage climate-related health emergencies and to remind residents about the instrument recycling initiative. These reminders may also have increased the recycling efforts.

2. Accreditation Council for Graduate Medical Education. Emergency Medicine Milestones. 2021. Available at: https://www.acgme.org/ globalassets/pdfs/milestones/emergencymedicinemilestones.pdf. Accessed September 28, 2024. 3. Moretti K. An education imperative: integrating climate change into the emergency medicine curriculum. AEM Educ Train. 2021;5(3):e10546. 4. Miracle M, Chekuri B, Weber K. A residency elective in sustainable health care. J Grad Med Educ. 2024;16(6 Suppl):157-8. 5. Bergquist M, Thiel M, Goldberg MH, et al. Field interventions for climate change mitigation behaviors: a second-order meta-analysis. Proc Natl Acad Sci U S A. 2023;120(13):e2214851120. 6. Hsu S, Thiel CL, Mello MJ, et al. Dumpster diving in the emergency department. West J Emerg Med. 2020;21(5):1211-7.

CONCLUSION Providing a financial incentive to residents for recycling efforts was modestly successful in encouraging them to participate in an instrument-recycling sustainability quality improvement initiative. Motivating busy clinicians to engage in sustainable practice is challenging; projects that prioritize systems-level changes may be more effective than those that require changes in individual clinical practices. ACKNOWLEDGMENTS Special thanks to the ED Green Team members Caroline Lee and Francesco Sergi for assisting with project implementation.

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7. Kaplan S, Sadler B, Little K, et al. Can sustainable hospitals help bend the health care cost curve? Issue Brief (Commonw Fund). 2012;29:1-14. 8. Or Z, Seppanen A-V. The role of the health sector in tackling climate change: a narrative review. Health Policy. 2024:143:105053. 9. Muldoon LB, Chan WW, Sabbagh SH, et al. Collecting unused medical supplies in emergency departments for responsible redistribution. J Emerg Med. 2019;57(1):29-35. 10. Chen EH, Losak MJ, Hernandez A, et al. Financial incentives to enhance participation of resident physicians in hospital-based quality improvement projects. Jt Comm J Qual Patient Saf. 2021;47(9):545-55.

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Scoping Review

Climate Change and Emergency Medicine: A Scoping Review Across Emergency Medicine Subspecialties Lea Moujaes, MD* Kayla Iuliucci, MD* Stefan Wheat, MD†

*Johns Hopkins University School of Medicine, Department of Emergency Medicine, Baltimore, Maryland † University of Washington, Department of Emergency Medicine, Seattle, Washington

Section Editor: Shahram Lotfipour, MD, MPH Submission history: Submitted September 30, 2025; Revision received January 7, 2026; Accepted January 7, 2026 Electronically published May 13, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.52979

Introduction: Climate change is reshaping emergency medicine (EM) practice through rising temperatures, extreme weather events, and deteriorating air quality. Emergency medicine serves as a critical frontline indicator for climate-sensitive health conditions, yet evidence describing climate impacts across EM subspecialties remains fragmented. This scoping review synthesizes existing literature at the intersection of climate change and EM to identify key findings, knowledge gaps, and priorities for building climate-resilient emergency care systems. Methods: We conducted a scoping review with reporting aligned to the PRISMA Extension for Scoping Reviews. We searched PubMed, Scopus, and Embase through March 2025, combining climate-related terms with EM terms. Two independent reviewers screened 794 articles, with 35 studies meeting inclusion criteria. We extracted data on study characteristics, climate exposures, EM outcomes, vulnerable populations, and system-level impacts across five EM subspecialties: emergency medical services; trauma; disaster medicine; toxicology; and mental health. Results: Across 35 studies spanning five EM subspecialties, most examined temperature-related exposures, with additional focus on extreme weather events and air quality. In emergency medical services, heatwaves and compound climate events were associated with increased call volume and operational strain, with vulnerabilities identified among older adults, working-age males, and populations in resource-limited settings. Trauma studies demonstrated consistent associations between ambient temperature and injury patterns, including traffic injuries, falls, and assaults with reproducible lag effects of 1-6 days. Disaster medicine studies highlighted critical preparedness and infrastructure gaps, including limited emergency management capacity, and predictable post-event surges in emergency department (ED) utilization. Toxicology studies linked higher temperatures and air quality changes to increased emergency visits for substance-related overdoses and respiratory conditions, while mental health studies consistently reported increased ED use and hospitalizations for psychiatric and substance use disorders during periods of extreme heat. Across subspecialties, socially marginalized populations, including individuals experiencing homelessness, those of lower socioeconomic status, older adults, and people with mental health or substance use disorders were disproportionately affected. Conclusion: Climate change is placing increasing strain on emergency care systems while amplifying existing health inequities. Current evidence is limited by geographic concentration in high-income settings, a predominant focus on temperature-related hazards, a lack of evaluated interventions, and insufficient integration of climate projections into health system planning. Addressing these gaps will be essential for developing climate-informed emergency medicine strategies capable of protecting vulnerable populations as climate-related health risks intensify. [West J Emerg Med. 2026;27(6.1)107–115.]

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Climate Change and EM: A Scoping Review Across EM Subspecialties INTRODUCTION Climate change represents a critical population health emergency, fundamentally altering disease patterns and healthcare utilization while disproportionately impacting vulnerable communities.1,2 Rising global temperatures, increased frequency of extreme weather events, and deteriorating air quality are creating unprecedented challenges for healthcare systems worldwide, with emergency medicine (EM) at the frontline for climate-related health impacts among the most at-risk populations.3,4 Emergency departments and emergency medical services (EMS) function as critical safety nets for climate-sensitive health conditions, including heat emergencies, respiratory exacerbations, mental health concerns, and increased incidence of trauma. These climate-related presentations strain emergency care systems while highlighting the uneven distribution of climate health burdens across different populations and geographic regions.4,5 Beyond direct patient care, climate change poses operational challenges that threaten the delivery of equitable emergency care. Extreme weather events can overwhelm emergency services in vulnerable communities, disrupt transportation networks essential for accessing care, and damage healthcare infrastructure in areas with limited adaptive capacity.6,7 These cascading effects underscore the urgent need for resilient, climate-informed emergency care systems capable of protecting the most vulnerable during climate emergencies.8,9 While individual studies have documented associations between weather patterns and specific health outcomes,10–14 comprehensive understanding of climate impacts across EM subspecialties including EMS, trauma, toxicology, disaster medicine, and mental health remains fragmented, particularly among high-risk communities. Current EM training curricula provide limited guidance on climate-informed care, leaving practitioners underprepared to respond effectively to the growing frequency and intensity of climate-related disasters.15–17 This scoping review maps existing literature at the intersection of climate change and EM, identifying key findings, knowledge gaps, and educational needs across subspecialties with particular attention to vulnerable populations. By synthesizing evidence on climate exposures and emergency healthcare use, this review will inform development of climate-informed emergency care strategies essential for building resilient, equitable EM systems capable of effectively serving vulnerable communities facing accelerating climate impacts. METHODS Study Design We conducted a scoping review to characterize existing literature at the intersection of climate change and EM across five subspecialties: EMS; trauma; disaster medicine;

Western Journal of Emergency Medicine

Moujaes et al. Population Health Research Capsule What do we already know about this issue? Climate change increases ED visits, EMS demand, and worsens outcomes, disproportionately affecting vulnerable populations. What was the research question? What are climate change impacts, gaps, and priorities across EM subspecialties? What was the major finding of the study? Across 35 studies, heat exposure was associated with increased injury risk (RR 1.08/°C, 95% CI 1.03–1.14) and higher emergency care utilization. How does this improve population health? We identify urgent gaps to guide climateresilient emergency systems and mitigate escalating, inequitable climate health impacts.

toxicology; and mental health. This scoping review was conducted to map the breadth of evidence and identify knowledge gaps across heterogeneous exposures, outcomes and study designs. Reporting of this review aligns with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses–Extension for Scoping Reviews. Search Strategy We conducted comprehensive searches in PubMed, Scopus, and Embase through March 2025 in collaboration with a medical librarian. We used controlled vocabulary (MeSH, Emtree) and free-text terms combining climaterelated terms (“climate change,” “global warming,” “extreme weather,” “heat wave”) with EM terms (“emergency medicine,” “emergency department,” “emergency medical services”). Google Scholar was searched for additional gray literature. Gray literature was defined as non–peer-reviewed scholarly content indexed within Google Scholar, such as reports, theses, or conference proceedings. We conducted searches using predefined strategy and fixed time window; studies published after completion of the initial search were not eligible for inclusion. ELIGIBILITY CRITERIA Inclusion criteria were as follows: articles discussing climate change or environmental exposures/events related to

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EM subspecialties, published in English, describing empirical research, interventions, or conceptual frameworks. Exclusion criteria were articles not addressing EM contexts or consisting solely of editorials without empirical content.

evidence of heat adaptation in chronically warmer areas.18 In Queensland, Australia, ambulance calls increased by 12.68% during heatwaves, with the largest proportional increases occurring during low- and severe-intensity events and among residents of very remote areas and major cities.19 Injuryrelated EMS demand was also climate-sensitive. In Chengdu, China, temperatures above 17.9 °C were associated with higher injury risk (risk ratio [RR] 1.08 per 1 °C increase, 95% CI, 1.03–1.14), peaking at 2–4 days.20 In Shenzhen, China, compound cold and strong monsoon events, and periods of low temperatures accompanied by heavy precipitation, were associated with increased all-cause calls (cumulative RR [CRR] 1.401) and endocrine-related calls (CRR 1.641), while compound heat waves combined with lightning significantly impacted digestive and endocrine disease presentations, as reported in observational analyses.21 Consensus-building studies, including Delphi methods that synthesize expert agreement across multiple rounds of structure surveys, further underscored systemic vulnerabilities. A Finnish Delphi study with EMS and emergency department experts identified 14 climate-related challenges across health impacts, workload, operational strain, and societal disruption.6 An international Delphi study with experts from multiple countries highlighted 18 consensus statements on heat wave–related overload, underscoring disparities between the income level of countries and the need for system-level adaptation planning.22

Study Selection After duplicate removal, 794 articles underwent title/ abstract screening by two independent reviewers. Articles meeting criteria advanced to full-text review, with 35 meeting final inclusion criteria. Data Extraction Two reviewers independently extracted data using a standardized abstraction framework, with discrepancies resolved through discussion. Extracted elements included study characteristics (design, location, population, subspecialty); climate exposures (temperature, extreme weather, air quality); EM outcomes (ED visits, EMS calls, hospitalizations), vulnerable populations and temporal patterns, and system-level impacts, including educational or operational considerations. RESULTS Thirty-five studies spanning five EM subspecialties met inclusion criteria: EMS (n = 13); trauma (n = 4); disaster medicine (n = 7); toxicology (n = 2); and mental health (n = 9). Studies were conducted primarily in Asia, Europe, North America, and Australia, with limited representation from low-resource regions. Observational designs predominated, including time-series analyses, retrospective ecological studies, case–crossover designs, Delphi methods, and qualitative approaches (Table 1).

Trauma Quantitative analyses consistently linked extreme temperatures to trauma-related emergencies. In Chongqing, China, high temperatures (32 °C vs 9 °C) increased risks of traffic accidents (CRR = 1.346, 95% CI, 1.167–1.552), assault-related injuries (CRR = 1.508), falls from height (CRR = 1.871), and sharp injuries (CRR = 2.112), while low temperatures (7 °C) increased fall risk (CRR = 1.220).23 In Chengdu, temperatures above 17.9 °C raised injury risk by 1.08-fold per 1 °C (95% CI, 1.03–1.14), with traffic accidents, poisoning, and falls most common.20 In Korea, nontraumatic injuries, defined as injuries such as drowning, poisoning,

Emergency Medical Services Most studies focused on temperature-related exposures, particularly heat waves and ambient temperature effects on EMS demand. In Japan, analysis of heat stroke–related ambulance transports across all 47 prefectures using wet-bulb globe temperature showed regional variation in risk, with

Table 1. Characteristics of a scoping review conducted to characterize existing literature at the intersection of climate change and emergency medicine. # Studies

Study locations

Study designs/methods

EMS

Subspecialty

Asia (7), Europe (3), Australia (2), Multinational (1)

Retrospective ecological/observational (4), Time-series (3), Case–crossover (2), Delphi (2), Prognostic (1), Qualitative (1)

Trauma

China (2), Korea (1), Pakistan (1)

Time series (3), Policy analysis (1)

Disaster

China, Pakistan, Taiwan, Ireland, USA

Observational (5), Policy analyses (2)

Toxicology

USA (California, nationwide projection)

Case-crossover observational (1), Modeling (1)

Brazil, Beijing, Toronto, USA, Canada, Sydney EMS, emergency medical services; USA, United States of America. Mental Health

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Observational (9)

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Climate Change and EM: A Scoping Review Across EM Subspecialties burns, electrical injuries, and other non-mechanical injury mechanisms, increased by 1.95% per °C (95% CI. 1.28– 2.62%), while traumatic injuries followed nonlinear patterns with a threshold around 0 °C.24 Across studies, consistent lag effects (1–6 days) and heightened risks among males and adults were observed. A policy analysis from Pakistan emphasized inadequate health expenditure, rural–urban disparities, and climate-related trauma burdens. 25

use or hospitalizations.33–40 In Brazil, lower socioeconomic status public patients were more vulnerable than private patients.36 In Beijing, increased projected burdens, defined as higher ED visits and hospital admissions, were observed for schizophrenia, substance-use disorders, women, and adults < 65 years of age.38 In Toronto, extreme heat increased ED visits for schizophrenia, mood, and neurotic disorders by 29% (99th vs 50th percentile).39 In the U.S., heat was linked to 3-4 fold increases in admissions for depression, schizophrenia, and bipolar disorder, based on nationwide time-stratified case–crossover analyses comparing exposure on admission days with matched control days33; and other national analyses documented increased ED visits and suicide risk during heat exposure.35,37,38 Canadian studies identified increased ED visits counts and hospital admissions for schizophrenia, dementia, and substance misuse during periods of elevated temperature.34 In Sydney, Australia, homeless men were identified as particularly vulnerable to heat-related illness with significant healthcare costs.40 Across subspecialties, several consistent patterns of vulnerabiliy emerged. Males and working-age adults faced higher risks in trauma and EMS studies, while older adults, individuals with substance use or psychiatric disorders, and socially marginalized populations such as individuals experiencing homelessness were disproportionately affected across multiple domains. Systems-level gaps in preparedness, resource allocation, and climate adaptation were identified in multiple studies. These vulnerabilities and system-level findings are summarized in Table 2.

Disaster Medicine Studies consistently revealed infrastructure and preparedness gaps. In China, only 36.5% of hospitals maintained emergency management offices, while 74% of nurses reported inadequate heat-preparedness knowledge.26 In Pakistan, limited health expenditure and rural–urban disparities constrained capacity.25 Temporal analyses showed rising disaster frequency. In Taiwan, extreme weather accounted for 92.2% of events reported to regional emergency medical operation centers (2014–2018).27 A global review reported a fivefold increase in major climate-related disasters over 50 years.28 In Ireland’s 2018 blizzard, emergency department volumes initially decreased during snowfall but surged afterward, with 71 cases distributed across injuries, medical, logistical, and social presentations.29 Operational adaptations, such as reallocation of emergency department and inpatient beds, workflow changes to maintain patient throughput, and flexible staffing and transfer practices implemented during disaster response, were also observed. During Hurricane Harvey, despite 74% inpatient bed loss, median emergency department length of stay decreased for admitted patients (591 vs 723 minutes) and discharges (261 vs 336 minutes), reflecting changes in care delivery processes implemented during disaster response rather than demonstrated causal effects.30 Toxicology Two United States (U.S.) studies linked climate exposures to toxicologic emergencies. In California, analysis of more than 3.4 million ED visits showed higher daily temperatures associated with overdoses, compared with non-overdose ED visits, particularly amphetamines (odds ratio 1.15, 95% CI, 1.09–1.22 comparing 95th vs 50th percentile), as well as cocaine and opioids. Effects were strongest for overdoses.31 A projection study estimated that under Representative Concentration Pathway (RCP) 4.5, a moderate emissions scenario, compared to RCP 8.5, a high emissions scenario, approximately 3,100 asthma ED visits and $1.7M in costs could be averted, underscoring benefits of climate mitigation.32 Mental Health All included studies reported positive associations between elevated temperatures and mental health–related ED

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DISCUSSION Emergency Medical Services Climate change is fundamentally altering the landscape of EMS through multiple interconnected pathways that extend beyond direct heat-related health impacts. By modifying environmental conditions, extreme weather patterns, and population vulnerability profiles, climate change is creating unprecedented challenges for prehospital emergency care systems worldwide.6 In this scoping review, we identified 13 papers examining associations between climate-related exposures and EMS use across diverse geographic contexts. Collectively, these studies demonstrate that temperature extremes and compound weather events are consistently associated with increased EMS demand, underscoring EMS as a critical frontline indicator for emerging climate-sensitive health risks.18,19,21 The predominant focus on temperature-related exposures reflects both the relative maturity of heat-health research and the immediate operational challenges posed by extreme heat events to emergency medical systems. Several large-scale analyses demonstrated graded, nonlinear, or threshold-based associations between ambient temperature and EMS utilization, with

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Table 2. Climate vulnerabilities and policy implications identified in a scoping review conducted to characterize existing literature at the intersection of climate change and emergency medicine. Subspecialty

Climate Vulnerable Populations

Policy/Practice Gaps

EMS

Males, working-age adults (18–44), elderly ≥ 65; disparities between income-level countries

Lack of EMS adaptation planning; disparities in resources between highand low-income regions; limited system-level strategies for compound climate events

Trauma

Males, adults 18–59, elderly ≥ 65; lag effects 1–6 days

No training/educational interventions identified; inadequate trauma system preparedness in climate-vulnerable regions (e.g., Pakistan); translational gap from data to protocols

Disaster

Nurses with low preparedness (74% lacked knowledge); rural vs urban disparities; varied event patterns by disaster type

Critical gaps in disaster preparedness infrastructure; limited hospital emergency management offices; need for structured training programs and resilient infrastructure

Toxicology

Individuals with substance use disorders (amphetamine, cocaine, opioids); asthma patients in high-ozone areas

Overdose risks exacerbated by rising temperatures; need for integrated heat- and climate-adapted substance use interventions; importance of climate mitigation for respiratory outcomes

Mental Health Women, youth, psychotic and substanceuse disorders, homeless, low SES, dementia patients

Inadequate integration of climate risk into mental health systems; lack of preventive strategies for vulnerable groups; need for heat-adaptive services and early-warning interventions

EMS, emergency medical services; SES, socioeconomic status.

evidence suggesting partial regional adaptation in chronically warmer settings.18 However, elevated risks persisted during extreme heat events, particularly among older adults, indicating that adaptation remains incomplete and unevenly distributed.18,19 Studies examining compound weather exposures suggest that simultaneous hazards, such as low temperature combined with heavy precipitation, may amplify EMS demand beyond what is captured by single-exposure frameworks.21 These findings highlight the importance of moving beyond isolated climate variables toward more integrated exposure models that better reflect real-word conditions.21 Across EMS literature, several limitations were consistent, including reliance on ecological (population-level) study designs, limited representation of low-resource settings, and minimal integration of climate projections. These gaps constrain the ability of EMS systems to anticipate future demand and to design proactive, climate-informed response strategies, reinforcing the need for broader geographic coverage and forward-looking analysis.22,41 Trauma Building on the evidence that heat contributes to surges in EMS demand, we identified four studies examining association between temperature and trauma-related emergency care utilization. While multiple environmental pathways may influence injury risk, including occupational exposures, behavioral changes, and infrastructure vulnerabilities, the four studies reviewed here focus specifically on temperature as a primary exposure of interest. Together, they demonstrate that fluctuations in temperature, particularly extreme heat, are associated with consistent

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patterns of trauma-related demand for EMS and ED use across diverse geographic and socioeconomic settings.20,23–25 Across studies conducted in China and South Korea, increases in temperature were associated with higher volumes of trauma-related emergency presentations across multiple injury categories, including traffic accidents and falls. 20,23 Several analyses reported nonlinear or threshold-based associations between temperature and injury-related utilization;23,24 however, given the observational nature of the included studies, the available evidence does not permit determination of causal mechanisms or formal dose–response relationships. Despite differences in climate, methodology, and population demographics, males and young to middle-aged adults were consistently identified as groups experiencing higher temperature-related trauma burden. These patterns may reflect occupational exposures, behavioral changes, or increased outdoor activity during warmer conditions. However, all included studies were observational, limiting causal inference.20,23–25 Notably, none of the included trauma studies evaluated preventive or adaptive interventions such as responder training, early warning systems, or public education strategies, despite the predictability of temperature-related injury patterns. This absence highlights a translational gap between epidemiologic evidence and actionable trauma prevention strategies, a theme echoed across other EM subspecialties and further detailed in the Common Gaps and Priorities section. Disaster Medicine Beyond injuries linked to heat and behavior, climate change also magnifies large-scale disasters that disrupt entire

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Climate Change and EM: A Scoping Review Across EM Subspecialties emergency care systems. Seven studies reviewed here showed that climate-related events consistently produced predictable surges in healthcare utilization, exposed systemic weaknesses, and highlighted opportunities for adaptation.26,27,29,30 Common vulnerabilities emerged across diverse hazards and geographies: inadequate infrastructure; rural–urban disparities; insufficient staffing; and gaps between perceived and actual preparedness. Several studies documented predictable temporal patterns of healthcare demand surrounding disaster events, yet none evaluated systematic educational interventions or formal clinician training, leaving a critical translational gap between surveillance and actionable preparedness. Equity dimensions were particularly pronounced. Highincome countries leveraged sophisticated data systems and analytic approaches to quantify disaster-related health risks, while studies from Pakistan and other resource-limited settings highlighted fundamental deficits in infrastructure, staffing, and financing that constrained emergency response capacity.25 These disparities emphasize the urgency of prioritizing adaptive capacity building in settings where baseline resources are lowest, and climate vulnerability is greatest. Operational adaptations, defined as changes in the ED workflows, staffing models, or care delivery processes implemented during climate-related disasters, were also described. During Hurricane Harvey, despite a reported 74% loss of inpatient bed capacity, median ED length of stay decreased for both admitted patients and discharges, reflecting changes in care delivery processes implemented during crisis response rather than evidence of causal improvement attributable to specific interventions.30 Importantly, the study did not report quantitative staffing increases or workforce expansion; observed differences were attributed to processlevel adaptations in patient flow and care delivery under disaster conditions rather than to increased staffing. While these findings suggest that disaster conditions can catalyze innovation, they should not obscure the profound human, operational, and economic costs associated with climatedriven disasters. Despite these observations, important limitations persist. Most disaster-focused studies examined single hazards, lacked integration with climate projection models, and did not account for compound or cascading events that may pose the greatest risks to emergency care systems. At the policy level, frameworks such as the Sendai Framework for Disaster Risk Reduction emphasize the role of health systems in disaster preparedness and resilience, reflecting global recognition of healthcare as a core component of disaster risk production. However, substantial gaps remain between policy commitments and on-the-ground implementation.42 Together, these findings underscore the urgent need for proactive, climate-informed disaster preparedness and align with the shared research and policy priorities detailed in the Common Gaps and Priorities section.

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Toxicology Our review identified two studies directly linking climate-related exposures—heat and ozone—to ED visits for drug-related toxicity and asthma. These studies underscore the emergency department’s critical role as a frontline detector for emerging climate-sensitive toxicologic harms, while also illustrating the limitations of existing evidence. Traditional toxicology frameworks, which often examine single chemicals under static conditions, may not adequately capture the dynamic, interacting exposures now emerging under climate change43,44 Social Vulnerabilities and Mental Health This review adds to the growing evidence that climate change directly and indirectly worsens mental health, increasing demand on EDs. Consistent with existing literature, we found that rising temperatures and heatwaves were strongly associated with higher ED use for a range of mental health disorders, including schizophrenia, depression, bipolar disorder, substance misuse, and personality disorders. These findings align with previous work showing that both acute climate-related events and chronic environmental stressors can trigger or exacerbate mental illness.45–47 Importantly, our review also highlighted the disproportionate burden, manifested as higher ED use, among socially and economically marginalized groups, including individuals reliant on public healthcare systems and those experiencing homelessness, reinforcing how climate change amplifies existing inequities.46 While the studies reviewed focused primarily on heat exposure, broader literature documents indirect pathways through which climate hazards affect mental health, including trauma related to bushfires, flooding, displacement, and livelihood loss, contributing to post-traumatic stress disorder, depression, anxiety, and increased risk of substance misuse and violence.46,48 Air pollution has also emerged as an important contributor, with short-term exposures to fine particulate matter and nitrogen dioxide associated with increased psychiatric hospital admissions for depression, schizophrenia, and bipolar disorder in older adults.33 Together, these findings underscore the multifaceted pathways by which climate hazards strain mental health and emergency care systems. Our focus on ED presentations excluded community-based or subclinical mental health impacts and did not systematically capture studies addressing indirect climate pathways. These limitations, along with the need for improved surveillance and integration of mental health with climate resilience planning, are expanded in the Common Gaps and Priorities section, which outlines potential directions for actionable next steps. Common Gaps and Priorities Consistent with the stated objective of this scoping review to identify knowledge gaps across EM subspecialties, we

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synthesized cross-cutting gaps and priorities that emerged across EMS, trauma, disaster medicine, toxicology, and mental health. This section reflects author synthesis informed by the reviewed literature, rather than findings abstracted directly from individual studies, and is intended to highlight shared vulnerabilities and strategic directions for future research and practice. Limited Geographic and Socioeconomic Scope Across all domains, the geographic and socioeconomic scope of existing evidence remains limited. Most studies were conducted in high-income countries with well-established emergency care systems, while regions experiencing the greatest climate vulnerability and resource constraints— particularly low- and middle-income countries—were underrepresented. This imbalance restricts generalizability and limits insight into settings where climate-related health impacts may be most severe.

shape exposure, access to care, or adaptive capacity. Addressing these disparities will require research and policy efforts that center equity and capacity building in high-risk, low-resource settings. Taken together, these gaps highlight several priorities for EM. These priorities reflect our interpretation informed by the reviewed literature and are intended to guide future research and preparedness efforts rather than represent evaluated interventions. Key priorities include the following: 1. Establishing international, multisite surveillance systems capable of detecting emerging hazards in real time 2. Integrating climate projection models directly with health service planning to guide infrastructure investment and workforce allocation 3. Designing and rigorously evaluating targeted interventions, such as climate-triggered EMS dispatch algorithms, heat-resilient power and water systems, and mental health integration into disaster planning, to enhance system resilience 4. Prioritizing capacity building and policy development in the low-resource, high-risk settings

Methodological Constraints Methodological limitations were pervasive. The literature was dominated by ecological and retrospective observational designs, with limited use of individual-level data, prospective approaches, or integration of climate projection models. As a result, causal inference remains limited, and the ability to anticipate future emergency care demand under evolving climate scenarios is underdeveloped.

Translational Gaps Despite increasingly consistent documentation of climaterelated surges in emergency care utilization, few studies evaluated adaptive interventions. Early warning systems, workforce adaptation strategies, resilient infrastructure design, and community-based prevention efforts were rarely assessed, leaving a persistent translational gap between epidemiologic evidence and actionable preparedness.

LIMITATIONS This review has several limitations. Most included studies focused on temperature-related exposures, with far fewer examining hazards such as wildfire smoke, flooding, or compound climate events. Evidence was also uneven across subspecialties: EMS, trauma, and mental health were relatively well represented, whereas toxicology and certain disaster domains had limited coverage. Further, most included studies were ecological or observational, limiting causal inference and leaving individual-level factors, such as socioeconomic status and comorbidities, insufficiently addressed. Few incorporated climate projection models, restricting insights into future emergency care demand under evolving climate scenarios. Research was also concentrated in high-income, data-rich settings, limiting applicability to lowand middle-income regions where climate impacts may be greatest and emergency care capacity most limited. Finally, heterogeneity in definitions of climate exposures and emergency care outcomes reduced comparability across studies. While some studies highlighted disparities affecting vulnerable populations, few systematically assessed equity, limiting the ability of this review to fully characterize differential impacts across social and demographic groups.

Equity and Health-System Resilience Equity considerations emerged as a central but incompletely addressed theme. Populations experiencing homelessness, rural communities, individuals with mental health or substance use disorders, those dependent on underresourced health systems were consistently identified as vulnerable, yet few studies examined how structural inequities

CONCLUSION Climate change is reshaping the landscape of emergency medicine across multiple subspecialties, driving predictable surges in demand, revealing systemic vulnerabilities, and amplifying inequities. Evidence from EMS, trauma, disaster medicine, toxicology, and mental health demonstrates that rising temperatures and extreme weather events are already

Narrow Hazard Focus A narrow focus on temperature-related exposures further constrained the evidence base. While heat represents a critical and well-characterized hazard, substantially fewer studies examined other climate-related threats, including wildfire smoke, flooding, extreme precipitation, and compound or cascading events. This emphasis may underestimate the full spectrum of climate-sensitive risks facing emergency care systems.

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Climate Change and EM: A Scoping Review Across EM Subspecialties straining frontline care. However, significant gaps remain, particularly regarding wildfire smoke, flooding, compound hazards, and toxicologic exposures. Current emergency care frameworks are insufficient for the multi-hazard realities of a warming world. Adaptation will require shifting from reactive, event-based responses toward proactive, climate-informed preparedness. Key priorities include improved surveillance, resilient infrastructure and workforce capacity, and the integration of equity and mental health considerations. Emergency medicine stands at a critical inflection point. By embracing climate resilience as a core competency, the specialty can mitigate immediate risks, safeguard vulnerable populations, and contribute to the development of sustainable, adaptive health systems for the future.

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environmental sustainability in emergency medicine: a narrative review. Ann Transl Med. 2025;13(3):31-31. 8. Arnell NW. The implications of climate change for emergency planning. Int J Disaster Risk Reduct. 2022;83:103425. 9. Guenther R, Balbus J. Primary Protection: Enhancing Health Care Resilience for a Changing Climate. U.S. Department of Health & Human Services; Centers for Disease Control and Prevention; The Kresge Foundation; 2014. Accessed September 11, 2025. https:// kresge.org/sites/default/files/Healthcare-Climate-ResilienceGuidance-HHS.pdf 10. Alahmad B, Khraishah H, Royé D, et al. Associations between extreme temperatures and cardiovascular cause-specific mortality: results from 27 countries. Circulation. 2023;147(1):35-46. 11. Liu J, Varghese BM, Hansen A, et al. Heat exposure and cardiovascular health outcomes: a systematic review and metaanalysis. Lancet Planet Health. 2022;6(6):e484-e495. 12. Abrignani MG, Lombardo A, Braschi A, et al. Climatic influences on

Address for Correspondence: Lea Moujaes, MD, Johns Hopkins Department of Emergency Medicine, 1830 East Monument Street Suite 6-100, Baltimore, MD 21287. Email: lmoujae1@jhu.edu.

cardiovascular diseases. World J Cardiol. 2022;14(3):152-169. 13. Thomson MC, Stanberry LR. Climate change and vectorborne diseases. N Engl J Med. 2022;387(21):1969-1978.

14. Rocklöv J, Dubrow R. Climate change: an enduring challenge for vector-borne disease prevention and control. Nat Immunol. 2020;21(5):479-483. 15. Moretti K, Rublee C, Robison L, et al. Attitudes of US emergency medicine program directors towards the integration of climate change and sustainability in emergency medicine residency curricula. J Clim

Change Health. 2023;9:100199. 16. Cois A, Kirkpatrick S, Herrin R. Climate change curricula in US graduate medical education: a scoping review. J Grad Med Educ. 2024;16(6 Suppl):69-77. 17. Dresser C, Wiskel T, Giudice C, et al. A graduate medical education fellowship in climate change and human health: experience and

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38. Niu YL, Lu F, Liu XJ, et al. Global climate change: effects of future temperatures on emergency department visits for mental disorders in

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34. Lavigne E, Gasparrini A, Wang X, et al. Extreme ambient temperatures and cardiorespiratory emergency room visits:

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Brief Review

Mechanisms and Intervention Strategies for Heat StrokeAssociated Myocardial Dysfunction: A Narrative Review Yan Zhuang, PhD*†o Xiao-huan Zhuang, MMBS*†o Xin-yuan Zhang, MMBS*† Da-Cheng Wang, MD*† Yan Yang, MMed*†

*Affiliated Hospital of Nanjing University of Chinese Medicine, Department of Critical Care Medicine, Nanjing, Jiangsu, China † Jiangsu Province Hospital of Chinese Medicine, Department of Critical Care Medicine, Nanjing, Jiangsu, China o Co-first authors

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted October 5, 2025; Revision received January 30, 2026; Accepted February 5, 2026 Electronically published May 13, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.53045

Introduction: Heatstroke is a life-threatening condition defined by a core body temperature exceeding 40° C and central nervous system dysfunction. Its onset is potentiated by high heat and humidity, especially if superimposed upon high thermal loads due to exertion or to impaired ability to sweat as associated with the use of certain medications. The condition can trigger systemic inflammation and potentially fatal multi-organ failure. The heart is a primary organ affected; heatstroke-associated myocardial dysfunction may present as tachycardia, arrhythmias, heart failure, or ischemic injury. Methods: This narrative review was informed by a structured search of PubMed and Embase. The search focused on literature from the past 10 years, supplemented by earlier seminal studies where necessary. Key search terms included heatstroke, myocardial injury, dysfunction, biomarkers, cooling strategies, monitoring, and circulatory support. We prioritized human clinical studies, reviews, and consensus statements on acute management, along with preclinical studies. Results: Heatstroke-associated myocardial dysfunction has a multifactorial pathophysiology involving direct thermal cytotoxicity, systemic inflammation, endothelial injury, coagulopathy, mitochondrial dysfunction, and dysregulated cell death. Cardiac manifestations include myocardial injury, arrhythmia, and ventricular dysfunction. Early diagnosis requires an electrocardiogram, cardiac biomarkers, and echocardiography. Management is centered on rapid cooling, hemodynamic support, and close monitoring. Refractory cases may require invasive temperature control or mechanical circulatory support. Conclusion: Heatstroke-associated myocardial dysfunction is a clinically important and potentially reversible complication. Timely cooling, vigilant cardiovascular assessment, and supportive management remain central to care, while targeted therapies and refined risk-stratification strategies require further clinical investigation. [West J Emerg Med. 2026;27(6.1)116–123.]

INTRODUCTION Global warming and related environmental changes have driven an increase in the number of extreme heat events, which currently account for an estimated 490,000 annual deaths worldwide. Modeling studies indicate a pronounced increase in heat-related fatalities, with projections suggesting

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a near twofold rise in global mortality between 2030–2050.1– 3 Heatstroke, a life-threatening condition defined by a core body temperature > 40 °C (104 °F) accompanied by central nervous system dysfunction, is commonly classified into two subtypes based on etiology: classic heatstroke, triggered by passive heat exposure; and exertional heatstroke, associated

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with physical exertion.4 Cardiac dysfunction is a prevalent complication of heatstroke, affecting up to 65.2% of patients with multiorgan failure. Heatstroke-associated myocardial dysfunction (HSMD) encompasses a broad spectrum of electrical and mechanical abnormalities, including sinus tachycardia, atrial and ventricular arrhythmias, and conduction disturbances.5,6 Elevations in cardiac troponins and natriuretic peptides are frequently observed and are associated with adverse outcomes. Emerging evidence suggests that endothelial-derived and extracellular vesicle–related biomarkers, such as von Willebrand factor, soluble thrombomodulin, and histone H3, may further refine risk stratification; however, heterogeneity in sampling windows, assay platforms, and outcome definitions limits direct comparability across studies. Prompt recognition of myocardial involvement is, therefore, critical. Early, staged interventions—including rapid cooling, hemodynamic-guided resuscitation, and continuous electrocardiographic and echocardiographic monitoring—are essential. Timely escalation to advanced temperature control or temporary mechanical circulatory support may be lifesaving; in selected cases, reversible myocardial depression has been reported.7 In this narrative review we aimed to synthesize the clinical manifestations and pathophysiological mechanisms of HS-MD, critically appraise current and emerging biomarkers, and propose a pragmatic, timewindowed management framework, while outlining priorities for future research. METHODS Literature Search Strategy This is a narrative review supported by a structured literature search. We searched PubMed and Embase, primarily focusing on studies published within the past 10 years, while also including selected earlier landmark studies where necessary to provide essential background. Our search strategy combined terms related to heatstroke and cardiac involvement, including (“heatstroke” OR “heat stroke” OR “exertional heat stroke” OR “classic heat stroke”) AND (myocard* OR cardiac OR “myocardial injury” OR “myocardial dysfunction” OR arrhythmia OR troponin OR echocardiograph*) AND (cooling OR resuscitation OR monitoring OR vasopressor* OR “mechanical circulatory support”). We also screened reference lists of relevant reviews and consensus statements to identify additional pertinent studies. We prioritized human clinical studies, narrative reviews, and guidelines or consensus statements relevant to the pathophysiology and acute management of HS-MD. Selected preclinical studies were included when they provided mechanistic insights with potential clinical relevance. We excluded non English-language articles without accessible full text and studies not related to cardiac involvement in heatstroke.

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Clinical Characteristics of Heatstroke-associated Myocardial Dysfunction Arrhythmias Within 24 hours of heatstroke onset, patients may develop a range of electrocardiographic (ECG) abnormalities, including sinus tachycardia, ventricular tachycardia, QTinterval prolongation, diffuse nonspecific ST–T changes, and ST–T alterations suggestive of myocardial ischemia.8 The incidence of atrial arrhythmias has been reported to reach up to 24%, while severe cases may present with ventricular tachycardia or even cardiac arrest.9,10 Atrioventricular conduction disturbances associated with heatstroke include PR-interval prolongation, intraventricular conduction delays, and left or right bundle branch block.11 QT- interval prolongation is a particularly common finding and may be partially attributable to electrolyte disturbances induced by heatstroke.12 Beyond the acute phase, heatstroke has also been associated with increased long-term cardiovascular risk.9,13 A 14-year follow-up study of discharged patients demonstrated a 3.9-fold increase in major adverse cardiovascular events and a 15-fold increase in the incidence of atrial fibrillation.14 Myocardial Injury At the molecular level, heatstroke can exert persistent effects on cellular function and epigenetic regulation, which may remain subclinical until unmasked by subsequent stressors or aging-related processes.15,16 Clinically, myocardial injury related to heatstroke poses a diagnostic challenge, as it can closely mimic acute coronary syndromes. Typical findings include territory-like ST-segment deviations and marked T-wave inversions on ECG.9 Elevations in cardiac troponin levels are common and carry important prognostic implications, with severe elevations associated with increased one-year mortality.17 Importantly, this pattern of myocardial injury is thought to reflect supply–demand mismatch and microvascular dysfunction rather than acute coronary thrombosis. Accordingly, a comprehensive diagnostic approach integrating clinical presentation, echocardiographic assessment, and biomarker kinetics is essential to distinguish HS-MD from type 1 (atherothrombotic) myocardial infarction. Heart Dysfunction Heat exposure leads to reductions in circulating blood volume and systemic vascular resistance, prompting compensatory increases in cardiac output to maintain blood pressure, tissue perfusion, and thermal homeostasis. Experimental and clinical studies have shown that for every 0.3 °C increase in core body temperature, myocardial contractility and cardiac output rise, while perfusion to certain organs decreases and cutaneous vasodilation intensifies to facilitate heat dissipation.18,19

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Table 1. Biomarkers for heatstroke-associated myocardial dysfunction, analytical characteristics, typical heatstroke patterns, and clinical utility. Pathway / what it reflects

Preferred sampling and units

hs-cTnI/T

Myocyte injury (thermal stress, microvascular dysfunction, supply–demand mismatch)

0 h, 3–6 h, 12–24 h; assayspecific 99th percentile and delta

BNP / NTproBNP

Ventricular wall stress and dysfunction

Serum myoglobin (sMb) / LDH

Syndecan-1

Prognostic / clinical use

Pitfalls, availability and turnaround

Key refs

Transient elevation after hyperthermia; may decline with effective cooling

Severity signal; predicts short- and long-term mortality; integrate with ECG/ echo to avoid misclassification as type-1 MI

Widely available in ED; rapid turnaround (≈1 h). Non-ACS elevations common in HS; influenced by exertion and renal dysfunction

0 h and 3–24 h; pg/mL

Frequently elevated; tracks LV dysfunction and volume stress

Complements echocardiography for triage, disposition, and prognosis

ED/ICU-available; turnaround ≈1–2 h. Affected by age, renal function, and atrial arrhythmias

Myocyte necrosis and systemic ischemic injury

sMb ≥1000 ng/mL; LDH elevated

Markedly elevated in severe HS, often with rhabdomyolysis

Better predictor of AKI and 90-day mortality than CK in EHS

Widely available; turnaround ≈1–2 h. Limited cardiac specificity; influenced by skeletal muscle injury

Endothelial glycocalyx shedding

0–24 h; ng/ mL

Elevated in moderate–severe HS

Correlates with organ dysfunction; surrogate of vascular injury

Research-oriented; limited ED availability; delayed turnaround; not myocardium-specific

Platelet count, HS-induced PT/INR, coagulopathy / fibrinogen, DIC overlap D-dimer

Baseline and Thrombocytopenia, Stage coagulopathy; serial (6–12 h) low fibrinogen, guide monitoring and elevated D-dimer escalation

Widely available; rapid turnaround. Affected by transfusion, hypothermia, liver dysfunction

IL-6 / HMGB1

Systemic inflammation and DAMP release

Early (0–6 h) and trend

Peaks around hyperthermia or early cooling

Global severity adjunct; may signal escalation

Limited routine availability; delayed turnaround; nonspecific

Circulating endothelial cells

Endothelial injury

0–24 h; specialized platforms

Elevated with severe endothelial damage

Research use; potential risk stratifier

Specialized assays only; pre-analytical variability

42,43

EV-histone H3

NET-related cellular injury

0–24 h; exploratory assays

Elevated in severe HS

Early severity signal (exploratory)

Research-only; assay standardization lacking

Biomarker

Typical HS pattern

Biomarkers listed in this table vary substantially in clinical availability and turnaround time. Cardiac troponins, natriuretic peptides, and routine coagulation parameters are widely available in most emergency departments and can typically be obtained within 1–2 hours, making them the most actionable tools for acute risk stratification. In contrast, markers of endothelial injury and inflammation (e.g., syndecan-1, IL-6, HMGB1, circulating endothelial cells, EV–histone H3) are primarily research-based, often require specialized assays, and are not routinely available for real-time emergency decision-making. Reported biomarker patterns should be interpreted in the clinical context of hyperthermia, exertion, renal function, and concomitant organ dysfunction. Elevations do not necessarily indicate primary ischemic heart disease and should be integrated with electrocardiography and echocardiography to guide management. h, hours; HS, heatstroke; HS-MD, heatstroke-associated myocardial dysfunction; hs-cTnI/T, high-sensitivity cardiac troponin I/T; BNP, B-type natriuretic peptide; LDH, lactate dehydrogenase; AKI, acute kidney injury; DIC, disseminated intravascular coagulation; DAMPs, danger-associated molecular patterns; EV, extracellular vesicle.

Older adults and patients with pre-existing cardiac disease often exhibit impaired cutaneous vasodilation and diminished cardiac reserve, rendering them particularly vulnerable to circulatory failure during heat stress. Extreme heat is associated with increased mortality across all age groups, with

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individuals with chronic diseases—especially cardiovascular disease—at disproportionately higher risk.20 A multinational analysis across 27 countries reported that heat-related heart failure accounted for approximately 0.26% of cardiovascular deaths.21 In addition, epidemiological data indicate that

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extreme heat exposure is associated with a 12% increase in heart failure–related mortality.22 Pathophysiology of Heatstroke-Associated Myocardial Dysfunction Heatstroke-associated myocardial dysfunction results from the combined effects of direct thermal injury and systemic physiological derangements induced by extreme hyperthermia. Epidemiological studies consistently associate heat exposure with increased cardiovascular morbidity and mortality; however, myocardial impairment in heatstroke differs fundamentally from primary ischemic heart disease and is often functional, dynamic, and potentially reversible.23–25 Direct Thermal Injury to Cardiomyocytes At the cellular level, extreme hyperthermia exerts direct cytotoxic effects on cardiomyocytes. Elevated core temperatures disrupt protein conformation, impair calcium homeostasis, and alter membrane integrity, leading to reduced myocardial contractility and electrical instability.1,20 These temperature-dependent changes provide a mechanistic explanation for the frequent occurrence of arrhythmias, transient systolic dysfunction, and repolarization abnormalities observed during acute heatstroke.26,27

temperature reduction, restoration of circulating volume and perfusion, and attenuation of systemic inflammation may lead to recovery of cardiac function over hours to days. This predominantly functional and inflammatory pattern of myocardial injury highlights the importance of early recognition and aggressive supportive management, rather than therapeutic strategies aimed at irreversible structural myocardial damage.6,12,36 A schematic overview of the principal mechanistic pathways involved in HS-MD is presented in Figure 1. Management of Heatstroke-Associated Myocardial Dysfunction Early Recognition and Risk Stratification Early recognition of myocardial involvement is essential in patients with heatstroke, as timely identification informs monitoring intensity, disposition, and subsequent management. Clinical suspicion should be heightened in the presence of arrhythmias, hemodynamic instability, or signs of cardiac dysfunction.45 Electrocardiography remains a first-line tool for detecting conduction abnormalities and malignant arrhythmias and should be performed early in the course of evaluation.11,46,47 Cardiac biomarkers play an important adjunctive role in

Systemic Inflammation and Endothelial Dysfunction Beyond direct thermal effects, heatstroke provokes a systemic inflammatory response that resembles sepsis-like physiology. Heat-induced cellular injury triggers widespread inflammatory activation, accompanied by endothelial dysfunction and increased vascular permeability. These processes promote microvascular dysregulation and impair effective tissue perfusion.28,29 Within the myocardium, inflammatory mediators and endothelial injury compromise oxygen delivery and myocardial energetics, contributing to myocardial depression even in the absence of obstructive coronary artery disease.30–32 Microcirculatory and Metabolic Disturbances Microcirculatory impairment further exacerbates myocardial dysfunction in heatstroke.33 Hypovolemia, peripheral vasodilation, and endothelial injury reduce effective circulating volume and limit coronary microvascular perfusion.34 In parallel, metabolic disturbances—particularly mitochondrial dysfunction and impaired adenosophine triphosphate generation—restrict the heart’s ability to meet increased metabolic demands during heat stress. Together, these alterations predispose susceptible patients to acute heart failure, shock, or circulatory collapse.35 Reversibility and Clinical Implications Importantly, myocardial dysfunction in heatstroke is frequently reversible with timely intervention. Rapid

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Figure 1. Pathophysiology of heatstroke-associated myocardial dysfunction. Extreme hyperthermia leads to myocardial dysfunction through four inter-related pathophysiological mechanisms.1) inflammatory response: heat-induced cellular injury triggers release of damage-associated molecular patterns and pro-inflammatory cytokines, resulting in systemic inflammation and cardiomyocyte injury. 2) Mitochondrial dysfunction and oxidative stress: excessive heat and metabolic stress impair mitochondrial function, promote oxidative stress, and reduce energy production, contributing to myocardial depression and electrical instability. 3) Endothelial and microcirculatory injury: endothelial dysfunction, reduced nitric oxide bioavailability, and microthrombosis impair myocardial perfusion and exacerbate ischemia-like injury. 4) Direct thermal cytotoxicity: extreme temperatures cause protein denaturation, membrane damage, and cardiomyocyte death. These mechanisms converge to produce clinically relevant myocardial dysfunction, which is often functional and potentially reversible with timely intervention.

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Mechanisms and Intervention Strategies for Heatstroke-associated Myocardial Dysfunction risk stratification. Elevations in cardiac troponins are common in heatstroke and may reflect myocardial injury related to supply–demand mismatch and microvascular dysfunction rather than acute coronary thrombosis.37,48 When interpreted dynamically, troponin trends can provide prognostic information and help differentiate transient functional myocardial injury from evolving ischemic events. Natriuretic peptides, including B-type natriuretic peptide, may further assist in identifying patients with myocardial stress or overt cardiac dysfunction.49 Markers of endothelial injury and inflammation have also been explored as potential tools for early risk assessment. Circulating endothelial cells, adhesion molecules, thrombomodulin, and von Willebrand factor antigens may reflect microvascular injury and endothelial dysfunction in severe heatstroke. Although these biomarkers are not routinely available in all clinical settings, their presence highlights the systemic vascular involvement underlying heatstrokeassociated myocardial dysfunction. When available, bedside echocardiography provides complementary information by assessing ventricular function, preload status, and potential reversible myocardial depression. Integration of clinical findings, ECG changes, biomarker trends, and echocardiographic assessment allow a more comprehensive and clinically meaningful stratification of cardiovascular risk in patients with heatstroke. Rapid Temperature Control: Principles and Comparative Strategies Rapid reduction of core body temperature remains the cornerstone of heatstroke management and is particularly critical in patients with suspected HS-MD.50 The magnitude and duration of hyperthermia are closely associated with myocardial injury, arrhythmias, and hemodynamic compromise; therefore, cooling should be initiated as early as possible and continued until target temperature is achieved. Goals and Timing of Cooling The primary objective of therapeutic cooling is the rapid reduction of core temperature to below 39° C, followed by maintenance to prevent rebound hyperthermia.51 A cooling rate exceeding 0.15 °C/minute is critical for survival and is associated with significantly reduced fatality and complication rates.52 Clinical outcomes exhibit a clear time-dependent relationship with cooling speed; delays in temperature reduction are linked to more severe neurological and cardiovascular injury. In patients with pre-existing myocardial dysfunction, inadequate or delayed cooling can exacerbate myocardial depression and trigger malignant arrhythmias. External Cooling Methods External cooling techniques are considered first-line therapy in most patients with heatstroke. Immediate cooling

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measures were implemented, which included giving cold intravenous fluids, placing ice packs, using lukewarm water and fans, applying wet towels, and using full-body medical cooling suits such as CarbonCool.53,54 Ice-water immersion achieves the most rapid cooling rates and is particularly effective in exertional heatstroke.55,56 However, its use may be limited in patients with altered mental status, advanced age, or cardiovascular instability. Evaporative and convective cooling methods, including mist-and-fan techniques and surface cooling devices, are more commonly employed in emergency and intensive care settings. Although these methods may achieve slower cooling rates, they allow improved access for airway management, cardiovascular monitoring, and hemodynamic support, which is especially relevant in patients with myocardial involvement.18,57 Intravascular and Invasive Cooling Intravascular or other invasive cooling strategies may be considered when external cooling measures fail to achieve adequate temperature control or are contraindicated. The available evidence supporting these approaches in heatstroke is limited and largely anecdotal. Reported cases suggest that invasive cooling may facilitate effective temperature reduction in selected patients with severe or refractory hyperthermia.58 At present, these techniques should be regarded as rescue strategies rather than routine therapy, and their use should be individualized based on the patient’s condition, resource availability, and procedural risk.59 Hemodynamic Support and Volume Management Hemodynamic management should be tailored to the presence and severity of myocardial dysfunction. Initial fluid resuscitation is often required to address hypovolemia; however, excessive fluid administration may exacerbate myocardial stress and pulmonary congestion in patients with impaired cardiac function.12 Dynamic assessment of volume responsiveness, integration of bedside echocardiography, and close monitoring of perfusion parameters are recommended. In patients with persistent hypotension despite appropriate volume resuscitation, vasopressor support may be required, with careful titration to maintain end-organ perfusion while avoiding excessive afterload.6,18 Cardiovascular Monitoring and Support Continuous cardiovascular monitoring is recommended in patients with suspected HS-MD. Continuous ECG monitoring enables early detection and prompt management of arrhythmias, which may occur during both the hyperthermic phase and the cooling process. Serial assessment of cardiac biomarkers may provide insight into the progression or resolution of myocardial injury. Echocardiography, when available, should be used to monitor ventricular function and

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guide ongoing hemodynamic management. Supportive care should focus on optimizing oxygen delivery, correcting electrolyte disturbances, and managing arrhythmias in accordance with standard critical care principles.9

hemodynamic support, and continuous cardiovascular monitoring remain the cornerstones of management in emergency and critical care settings. Improved awareness and further clinical studies are needed to refine risk stratification and optimize supportive strategies for this vulnerable patient population.

Advanced and Rescue Therapies In rare cases complicated by refractory shock or cardiac arrest, escalation to advanced supportive therapies may be considered. Mechanical circulatory support, such as venoarterial extracorporeal membrane oxygenation, has been reported in isolated cases of severe heatstroke with cardiovascular collapse.60,61 However, the available evidence remains limited, and patient selection should be individualized. Decisions regarding escalation to advanced support should consider the reversibility of organ dysfunction, neurological status, and overall prognosis.

Address for Correspondence: Yan Zhuang, MD, Affiliated Hospital of Nanjing University of Chinese Medicine, Department of Critical Care Medicine, Nanjing, Jiangsu 210000, China. Email: athena2004112@163.com. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare.

Pharmacologic and Experimental Approaches Several pharmacologic and experimental strategies, including antioxidant therapies and metabolic modulators such as L-carnitine, have been explored primarily in preclinical or experimental settings.62,63 Although these approaches offer mechanistic insights into potential myocardial protection during hyperthermia, their clinical efficacy and safety in HS-MD have not been established. At present, such strategies should be considered investigational and should not replace established temperature-directed and supportive management.3

Copyright: © 2026 Zhuang et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES 1. Desai Y, Khraishah H, Alahmad B. Heat and the heart. Yale J Biol Med. 2023;96:197-203. 2. Romanello M, Di Napoli C, Drummond P, et al. The 2022 report of the

LIMITATIONS This review has several limitations that should be acknowledged. First, as a narrative rather than a systematic review, the study is subject to selection and publication bias, and the included literature may not comprehensively represent all available evidence. Second, although a structured literature search was performed, we did not conduct formal study quality assessment or quantitative synthesis, which limits direct comparison across studies. Third, heterogeneity in study designs, patient populations, outcome definitions, and biomarker assays precludes firm conclusions regarding causality or the relative importance of specific mechanisms. Finally, much of the mechanistic evidence is derived from preclinical or observational studies, and its direct applicability to emergency and critical care practice requires further validation. These limitations underscore the need for well-designed prospective studies and translational research in this evolving field. CONCLUSION Heatstroke-associated myocardial dysfunction is a frequent and clinically significant complication of severe hyperthermia that is typically functional, inflammatory, and potentially reversible rather than ischemic in nature.57 Early recognition, prompt temperature control, individualized

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Lancet Countdown on Health and Climate Change: health at the mercy of fossil fuels. Lancet. 2022;400:1619-1654. 3. Kew MC, Tucker RB, Bersohn I, et al. The heart in heatstroke. Am Heart J. 1969;77:324-335. 4. Bouchama A, Abuyassin B, Lehe C, et al. Classic and exertional heatstroke. Nat Rev Dis Primers. 2022;8(1):8. 5. Garcia CK, Renteria LI, Leite-Santos G, et al. Exertional heat stroke: pathophysiology and risk factors. BMJ Med. 2022;1:e000239. 6. Peters A, Schneider A. Cardiovascular risks of climate change. Nat Rev Cardiol. 2021;18:1-2. 7. Marchand M, Gin K. The cardiovascular system in heat stroke. CJC Open. 2022;4:158-163. 8. Shimada M, Tsai B, Marshall JP. A case of heatstroke complicated by persistent ventricular tachycardia. J Emerg Med. 2015;48:31-34. 9. Paul A, Alex R, Jacob JR, et al. Effects of heat stroke on surface ECG: a study on clinical outcomes. Heart Asia. 2019;11:e011221. 10. Petropoulos ZE, Keogh SA, Jarquín E, et al. Heat stress and heat strain among outdoor workers in El Salvador and Nicaragua. J Expo Sci Environ Epidemiol. 2023;33:622-630. 11. Mimish L. Electrocardiographic findings in heat stroke and exhaustion: a study on Makkah pilgrims. J Saudi Heart Assoc. 2012;24:35-39. 12. Bathini T, Thongprayoon C, Petnak T, et al. Circulatory failure among

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heat-stressed human. Acta Physiol (Oxf). 2010;199:407-423. 19. Crandall CG, Wilson TE, Marving J, et al. Effects of passive heating

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23. Bauman J, Spano S, Storkan M. Heat-related illnesses. Emerg Med Clin North Am. 2024;42:485-492.

Public Health Prep. 2025;19:e153. 42. Truong SK, Katoh T, Mimuro S, et al. Inhalation of 2% hydrogen

24. Cramer MN, Gagnon D, Laitano O, et al. Human temperature

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glycocalyx in rats with heat stroke. Shock. 2021;56:593-600. 43. Iba T, Maier CL, Levi M, et al. Thromboinflammation and microcirculation

25. Wang Z, Zhu J, Zhang D, et al. The significant mechanism and treatments of cell death in heatstroke. Apoptosis. 2024;29:967-980.

damage in heatstroke. Minerva Med. 2024;115:191-202. 44. Murray KO, Clanton TL, Horowitz M. Epigenetic responses to heat:

26. De Vita A, Belmusto A, Di Perna F, et al. The impact of climate change and extreme weather conditions on cardiovascular health

from adaptation to maladaptation. Exp Physiol. 2022;107:1144-1158. 45. Roberts WO, Armstrong LE, Sawka MN, et al. ACSM expert

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pathophysiology and cell death pathways. Juntendo Med J. 2025;71:308-312.

2023;22:134-149. 46. Zhang Z, Wu X, Zou Z, et al. Heat stroke: pathogenesis, diagnosis,

28. Bouchama A, Abuyassin B, Lehe C, et al. Classic and exertional heatstroke. Nat Rev Dis Primers. 2022;8:8.

and current treatment. Ageing Res Rev. 2024;100:102409. 47. Bao C-H, Feng Q, Zhang C, et al. Heat stroke with significantly

29. Chen J, Ding C, Cao J, et al. Heat stress combined with

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or myocardial injury? Am J Med Sci. 2024;368:258-264. 48. Palasz J, Farooqi W, Musharraf MB, et al. Diagnostic biomarkers for

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30. Yamaga S, Aziz M, Murao A, et al. DAMPs and radiation injury. Front Immunol. 2024;15:1353990.

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- a significant biomarker of disease development and adverse

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Olympic Games Tokyo 2020. Br J Sports Med. 2021;55:1405-1410. 57. Liu J, Varghese BM, Hansen A, et al. Heat exposure and

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temperature and outcomes of patients with heat stroke. Intern Emerg Med. 2023;18:1831-1842.

analysis. Lancet Planet Health. 2022;6:e484-495. 58. Bursey MM, Galer M, Oh RC, et al. Successful management of

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severe exertional heat stroke with endovascular cooling after failure

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of standard cooling measures. J Emerg Med. 2019;57:e53-56. 59. Hamaya H, Hifumi T, Kawakita K, et al. Successful management of

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Expert Commentary

Cultivating Environmentally Sustainable Emergency Departments with GreenED Jennifer L. Wood, MBChB, BSc*† Alexander Robertson, MBChB*‡ Tim Spruell, MBChB, MSc*§ Zoe Steley, MBBS, BA, MA*||

*GreenED, Royal College of Emergency Medicine, London, United Kingdom † National Health Service Lothian, Environmental Sustainability Team, Edinburgh, United Kingdom ‡ National Health Service Fife, Victoria Hospital, Emergency Department, Kirkcaldy, United Kingdom § University Hospital Sussex, Emergency Department, Brighton, United Kingdom || Sydney Hospital and Syndey Eye Hospital, New South Wales, Australia

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted December 7, 2025; Revision received March 12, 2026; Accepted March 17, 2026 Electronically published July 16, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.61385

Introduction: Collective leadership within healthcare is critical if we are to deliver on net zero targets and provide high-value, low-carbon care to our patients. However, driving change in systems under considerable strain from crowding, limited resources, and increasingly complex caseloads can be a daunting task and often feels out of reach. In July 2023, the Royal College of Emergency Medicine (RCEM) launched a sustainability initiative to support environmentally sustainable healthcare within emergency departments (ED). This 12-month support and accreditation scheme centers around a framework of 36 actions and has been designed to make sustainability interventions accessible to staff, enabling individuals, groups, and networks to become leaders within their own spheres of influence and elicit measurable changes. The objective of this study was to evaluate the impact of the accreditation scheme over a 2-year period. Methods: The primary outcome measures were the financial and carbon savings made by participating sites. Secondary outcome measures were derived from a thematic analysis of written submissions, undertaken to identify co-benefits and generate qualitative insights into both barriers to, and enablers of, environmental sustainability interventions within EDs. Results: Five sites were successfully accredited for Bronze and Silver awards in 2024, and 10 sites for Bronze, Silver and Gold awards in 2025, with combined projected annual savings of £351,366 and 157,724 kg of carbon dioxide equivalent. Conclusion: To our knowledge, this is the first time that a collaborative, structured, dynamic, and scalable approach to sustainable healthcare in emergency medicine has been used worldwide. [West J Emerg Med. 2026;27(6.1)124–131.]

INTRODUCTION Sociopolitical factors are now the rate-limiting step in rolling out high-value, low-carbon healthcare.1 Collective leadership is, therefore, imperative if we are to stimulate the structural reorganisation and new behaviours within our healthcare system and society that are required to address the increasing presentations of climate crisis patients at the ‘front door’ in emergency medicine (EM).2,3 As a threat multiplier,

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the climate crisis will continue to exacerbate existing health and social inequalities for future generations and challenge our already struggling systems. In response to the existential threat of climate change, the UK’s National Health Service (NHS) committed to reaching net zero emissions in October 2020, becoming the world’s first health service to do so.4 However, the healthcare system itself compounds this crisis, generating around 4-6% of the UK’s total

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Wood et al. carbon footprint.5, 6 Some examples include the overuse of non-sterile gloves, which are derived from fossil fuels and often flown or shipped from Asia; meter dose inhalers, which contain a hydrofluoroalkane gas 1,300 times stronger than carbon dioxide and whose plastic, derived from fossil fuels, is currently difficult to recycle; and low-value radiology and pathology tests, which all have financial and environmental concerns, as well as patient safety concerns when inappropriately utilized.7-10 We commend NHS Scotland’s Climate Change Risk Assessments and Adaptation summary report and NHS England’s Green Plan guidance which help to identify the next steps in decarbonising the NHS. However, amid crowding, staff shortages, and increasingly complex presentations, many healthcare workers lack the time, knowledge, support, and confidence in their ability to enact behavioural and systemslevel change.11-13 The Royal College of Emergency Medicine (RCEM) launched a sustainability initiative called GreenED in July 2023, after a pilot study in England from 2021–2022.14 This framework of actions has been designed by emergency clinicians to help emergency department (ED) staff in high resource settings to reduce environmental impacts of clinical practice and departmental operations whilst quantifying carbon and financial savings associated with transitioning to highvalue, sustainable models of patient care. To our knowledge, this is the first time that a collaborative, structured, dynamic,

and scalable approach to sustainable healthcare in EM has been used. This brief report will discuss the scheme which consists of the development of the framework and share insights from the EDs that were accredited at Bronze, Silver, and Gold levels in 2024 and 2025. What is it? GreenED is a 12-month support and accreditation scheme that consists of evidence-based actions, structured into three levels by order of feasibility —immediate changes (Bronze); mid-term changes (Silver); and long-term changes (Gold)—to make an ED more environmentally sustainable (Figure 1). Sites typically progress through these levels in a stepwise manner. Whilst some resources are open access, sites can pay a fee (£2,200 as of 2026) to access further resources. These include an online portal with customized collated resources which equips participants to design and implement practical departmental changes, and monthly troubleshooting meetings facilitated by clinicians with sustainable healthcare expertise, which help to share achievements and identify barriers to action implementation. This iterative process enables participants to become leaders in their own spheres of influence, feeding innovative case studies back into the scheme to empower others and grow the evidence base for environmentally sustainable emergency healthcare.

Figure 1. GreenED Framework 3.0 Bronze, Silver and Gold levels (updated May 2025). This figure depicts the actions in Framework 3.0, separated into Bronze, Silver and Gold, that emergency departments (ED) can undertake to make their ED more environmentally sustainable over the short-term, mid-term, and long-term. respectively. ED, emergency department.

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Wood et al.

How was it created? In 2019 the RCEM established the Environmental Specialist Interest Group (ESIG) and tasked the appointed volunteers with developing ways to make daily clinical practice more environmentally sustainable. A working group of emergency physicians and advanced care practitioners from hospitals in the UK was assembled to discuss environmental sustainability actions which could be enacted in an ED setting. With potential actions identified, ESIG and the RCEM Quality Team collaborated with the founders of the Laboratory Efficiency Assessment Framework (LEAF), a certification in sustainable laboratory operations managed by University College London, on the proposed initial GreenED framework, termed Framework 1.0.15 An induction webinar was held in November 2021 for emergency clinicians interested in trialing the framework as pilot sites where the background to the Framework 1.0 was shared along with its potential to contribute towards the target of NHS net zero 2040 targets. Ten sites in England registered for an eight-month pilot. Initial seed funding of £83,000 from a healthcare public body allowed for the development of the framework and pilot project to be undertaken. Sites were provided with digital monthly catch ups with members of the GreenED team, the Framework 1.0, infographics, and a project folder where they could submit required reports (following a standardised reporting format) and evidence of their actions in the form of reports, photos, videos, slide decks and posters. Accreditations standards and minimum evidence requirements were developed with ESIG, LEAF and the RCEM quality directorate. Submissions were examined by members of the ESIG and LEAF teams at the end of the eight-month period and included discussions with the site leads. Eight of the sites were accredited with Bronze level awards. Feedback from sites and teams involved in the pilot was used to improve and develop the GreenED Framework 2.0 which was reviewed and endorsed by a healthcare public body. Improvements included the building of a customized online portal hosted by the RCEM and customized carbon calculators, along with some minor adjustments to the framework (difficult-to-attain actions were moved to Silver levels), and it was launched by the RCEM in July 2023 for sites in the UK to voluntarily sign up to. METHODS Participating groups worked through the GreenED Framework 2.0 in ‘communities of practice’ to enable collaboration and troubleshooting. Using the portal, sites submitted qualitative data about achieving actions and describing barriers faced, along with quantitative data using the customized portal carbon calculators for certain actions, including adjusting computer monitor brightness, low-carbon staff travel, using recycled paper, energy efficiency of light emitting diode (LED) lights, and use of cannulas. Carbon

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savings are measured using carbon dioxide equivalent (CO2e), a universally recognised metric that expresses the warming impact of all greenhouse gases in terms of the equivalent amount of CO2. Financial savings for each action were reported by sites according to the local procurement data in their ED in pound sterling. Savings categories were defined as Patient Pathways, Procurement, Energy, Waste, and Travel. Patient pathways included savings made in cannulation pathways, pathology/radiology savings, reduced non-sterile glove use, and switching from nitrous oxide to methoxyfluorane in the ED. Methoxyfluorane (Penthrox) has a longer duration of analgesia compared to nitrous oxide, can be delivered via a small hand-held inhaler, and has a significantly lower CO2e than nitrous oxide. Other pathways include the following: procurement savings related to recycled paper and reusing mobility aids; waste savings related to correct waste streaming between domestic, clinical, and recycling bins; energy savings from reducing monitor brightness/reducing time to idle, switching to LED lights and using sensors to reduce use in low-use areas; and travel savings related to staff changing modes of transport to work or by working remotely on non-clinical days. Assessors reviewed the quantitative savings submitted by sites along with the evidence submitted for these savings. Quantitative evidence was then sorted into savings categories as defined above and extrapolated to calculate projected annual financial and carbon savings. If sites were unable to produce sufficient evidence for their calculations (such as incomplete procurement data or savings which were part of a Trust-wide initiative as opposed to an ED-only initiative) these savings were not included in the final calculations in Tables 1 and 2. Institutional governance approval for the thematic analysis was obtained by the Clinical Effectiveness Team in a UK district general hospital. Using peer-reviewed standards, a pool of clinicians who assessed the submissions, performed a thematic analysis on the evidence from the five sites that submitted for accreditation in 2024. Each submission was reviewed separately by two assessors who created codes and identified initial themes. Themes from the written submissions were then shared with and collated by the GreenED team. The team also compiled the available data on carbon and financial savings from all sites that submitted in 2024 and 2025. RESULTS Summative quantitative results are listed in Table 1, highlighting projected financial savings per year that can be made whilst maintaining high-value, low-carbon clinical care, whilst Table 2 shows the individual sites projected carbon and cost savings made through the specific actions they chose to target. The GreenED actions resulted in clear financial and carbon savings for EDs. Quantitative savings are a

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Table 1. Projected quantitative savings rounded to the nearest pound (£) and kilogram from emergency departments using GreenED Framework 2.0. Patient Pathways (£)

Procurement (£)

2024 Projected Savings per year

£45,196

£7,857

Waste (£) Energy (£) £9,000

Total

2025 Projected Savings per year

£235,350

£7,010

£11, 244

£34,203

£287,807

119,762 kg

Total Savings

£280 546

£14, 867

£20, 244

£35, 708

£351, 366

157,724 kg

£1,505

£63,559

Total CO2 (kg) 37,962 kg

CO2,carbon dioxide.

Table 2. Site-specific projected annual savings in kilograms and pounds sterling (£) from emergency departments using GreenED Framework 2.0. Site 1 CO2e Site 1 Cost Site 2 CO2e Site 2 Cost Site 3 CO2e Site 3 Cost Site 4 CO2e Site 4 Cost (kg) (£) (kg) (£) (kg) (£) (kg) (£) Procurement

Waste

9000

Energy

433.13

497

3500

Pathways

16300

20,000

4152.51

7215.2

2974

53.28

1474.2

18000

Travel

Total

16733.13 kg

£20,497

4152.51 kg

£7215.2

6474 kg

£53.28

1474.2 kg

£27000

Site 5 CO2e (kg)

Site 5 Cost (£)

Site 6 CO2e (kg)

Site 6 Cost (£)

Site 7 CO2e (kg)

Site 7 Cost (£)

Site 8 CO2e (kg)

Site 8 Cost (£)

Procurement

4700

7785

1184

1235

Waste

1916.25

728

Energy

959.91

1008.37

745

1620

516

469.47

157.18

14723

Pathways

3468

6967

14852

1076

273

19466

Travel

9397

1910

Total

9127.91 kg

£8793.37

18293 kg

£17707

1592 kg

£469.47

4256.43 Kg

£34917

Site 9 CO2e (kg)

Site 9 Cost (£)

Site 10 CO2e (kg)

Site 10 Cost (£)

Site 11 CO2e Site 11 Cost Site 12 CO2e (kg) (£) (kg)

Site 12 Cost (£)

619

1943

720

Waste

109

3276

18488

7240

Energy

14800

16645

495

450

Pathways

65700

1281

2200

Travel

Total

619kg

£1943

877

£69054

34569

£26085

495

£450

Site 13 CO2e (kg)

Site 13 Cost Site 14 CO2e (£) (kg)

Site 14 Cost (£)

Site 15 CO2e Site 15 (kg) Cost (£)

Procurement

117

832

Waste

Energy

315

217.29

Pathways

27894

82932

23091

53200

Travel

Procurement

Total 432 £1049.29 27894 £82932 23091 £53200 The letter ‘N’ signifies that savings were submitted by sites but did not meet evidence standards and were excluded from the final dataset. CO2e, carbon dioxide equivalent.

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Wood et al. between hospital specialties and departments was reported. One site acknowledged that ‘conversations on sustainability that begin in [the] ED can be continued in primary care’, highlighting the interface between ED and primary care. Another site reported that after ‘the Sustainability fellow...for ED was employed...the momentum for sustainability work took off’, highlighting that strong environmental leadership within a collective can influence entire organisations. Multidisciplinary and inclusive teams are the most effective, ‘We have a large Initiative working group which meets up every three months. Our group includes doctors, nurses, advanced clinical practitioners, emergency nurse practitioners, managers, pharmacists, IT managers and sustainability managers.’ All sites reported that the success of the GreenED teams relied on inclusive and multidisciplinary teamwork; colleagues from different departments gravitated towards the group, breaking down professional silos. Many teams are now in regular contact with professionals in estates, domestics, sustainability as well as other community and hospital specialties.

The Initiative saves money and carbon. ‘We changed our screen brightness settings from 80% to 50%, installed a night mode to our screens and have communicated with our IT teams about changing our screensaver times. This is projected to Figure 2. An original GreenED Infographic which has since been save 3,500 kg CO2e per year.’ developed into2. GreenED Framework 3.0 (see Figure 1). Figure One of the original GreenED Infographics which has since All actions were designed to meet been the tripledeveloped bottom line, ED, emergency department. used to describe the intersection of improved patient care, into GreenED Framework 3.0 (see Figure 1). improved environmental sustainability, and financial savings. Addressing systemic waste by optimising IT settings, conservative projection due to limitations on data-gathering enhanced waste segregation as well as reducing low-value abilities in busy departments. This is being examined and care (such as unnecessary cannulation) resulted in reductions improved for Framework 3.0. Not all departments were able in carbon emissions, whilst also resulting in financial savings. to undertake comprehensive audits or submit projected If scaled across the hospital sites, the interventions could lead savings due to time and capacity constraints, and results are to significant cost and carbon savings. likely an underestimate. The thematic analysis revealed 28 different themes which Systemic barriers to progress were identified across a variety are showcased in Table 2. We discuss particular theme of actions. highlights below. ‘We have struggled to meet this target. Salbutamol DPI [dry powder inhaler] is not available on our Theme Highlights regional formulary’.’ Sustainability leads can effect change beyond the Systemic barriers to specific sustainability actions were emergency department, identified by sites during the monthly catch. ups and Sites reported that education and leadership from the accreditation process. Commonly encountered barriers GreenED team contributed to departmental level changes and included not having a kitchen to wash reusable cups, as well had a positive impact on department culture, leading to as dry powder inhalers not being available on regional sustainable changes in work and at home. Sites found that formularies. Departments would struggle to overcome these GreenED actions complemented Trust sustainability plans, barriers alone, but by identifying them through the and sustainable working practices were ‘shared and taken up accreditation process, the RCEM’s ESIG was able to advocate by other areas of the hospital’. Extensive co-operation for changes at regional and national levels.

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Table 3. Qualitative themes identified from thematic analysis of the Initiative site submissions 2024-2025. Thematic analysis from submissions Sustainability work was already underway in some EDs before starting GreenED accreditation.

Staff could still participate in the Initiative despite the limited time available.

The accreditation has led to innovative sustainability work both within and out of the ED.

The initiative saves money and carbon emissions.

Implementing clear signage on bins and teaching sessions on waste segregation are useful ways to instigate change.

The initiative has reduced single-use plastic waste.

Digital communication including Microsoft Teams, email, social media, and video are invaluable tools for a successful project.

Showing strong environmental leadership by having sustainability specific roles leads to quicker change both in the ED and wider hospital and can even change hospital culture.

Posters, notice boards and suggestion boxes are well used to exchange sustainability information with patients and staff.

ED staff already have concerns about our impact on the environment; listening to these concerns helps inform sustainability action and increases engagement.

GreenED teams are most effective when multidisciplinary, inclusive and with good working relationships with teams in the wider hospital.

Introducing new waste streams and rearranging bin placement were needed for departments to improve their waste segregation.

GreenED teams see that a close working relationship with Trust sustainability managers helps to progress projects.

Small-scale changes can empower staff and lead to positivity within the workforce.

Departments have used the champion role and badges to identify core GreenED members.

Changing firmly held ideas and behaviors about sustainability can be difficult.

Prioritising the Initiative by adding it as a standing agenda item both Initiative calculators help to quantify carbon and cost savings. departmentally and at Trust level saw improved project success. Regular meetings of the Initiative group are important to keep momentum going and check on progress.

Going through the GreenED process has spurred improvements in the sustainability of the built environment.

Teams have identified systemic barriers to progress in a variety of actions.

Remote working is well embedded in EDs and reduces the carbon footprint of travel to the hospital.

The initiative aligns with Trust sustainability plans and acts as a trigger for innovative NHS wide sustainability changes.

Listening to staff feedback on sustainability increases engagement.

Further work needs to be done to determine patient perspectives on sustainability.

Reductions in unnecessary cannulation saves time and improves patient experience.

Quality improvement methodology was used to implement changes.

There are a variety of sustainability resources and initiatives in the wider NHS that can be used to support work on GreenED.

In total, 28 themes were identified in the thematic analysis from the reports generated by the five sites who submitted for accreditation in 2024. ED, emergency department; NHS, National Health Service.

DISCUSSION Leadership, in the case of sustainable healthcare, is making change accessible, thus enabling individuals, groups and networks to become leaders in their own right. This produces collective leadership which has the capacity to activate socioeconomic tipping points and build alignment and commitment into organizations.3, 16 Analysis of the 15 sites achieving accreditation revealed that the RCEM GreenED initiative helped to facilitate staff action by providing structured guidance, resulting in coordination and continued effort in sustainable healthcare actions. The most successful sites had teams consisting of multidisciplinary members, and their improvements led to changes in the wider hospital, not just in their department. Through the site submissions, we have been able to identify systemic barriers, and this evidence has allowed us to advocate for change at national and

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international levels. Though an underestimate due to limitations of data collection, between 2024–2025 the 15 sites saved a total of £351,366 and 157.72 tonnes of CO2e per year, demonstrating that environmentally sustainable healthcare is beneficial for patients, staff, finances, and the planet. This is an underestimate, as some data were excluded due to insufficient evidence from sites due to participant capacity constraints, difficulties sourcing data due to limitations of the systems that we operate in or, in one case, because the savings made were felt to be attributable to a hospital-wide scheme of mobility aid reuse, as opposed to the ED spurring this itself. However, whilst a modest reduction in both pounds sterling and CO2e, it is the first quantified reduction using a tailored sustainability initiative in an ED setting that we know of. Participants were able to achieve this with no protected or paid time to carry out

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these initiatives, and whilst prioritizing emergency care in the context of departments which are facing record levels of ambulance waits and crowding leading to patient harm, moral injury, and staff turnover.17,18,19 As some of the first to carry out this work, we also wish to highlight that some systems and items have not had life cycle analyses carried out, which further complicates the ability to calculate carbon and financial savings. With participants feedback, data collection for CO2e and finances is developing rapidly and improving for Framework 3.0 (Figure 1), which was recently published on our website.14 Through the thematic analysis, we discovered that GreenED enables staff to adopt leadership roles within their circles of influence and can result in collective leadership at an organisational level. Sites reported the positive deconstruction of professional silos, a key factor in effecting behavioral change and scaling sustainable healthcare.20 LIMITATIONS There were several limitations to our evaluation. The first limitation is that participation in GreenED is voluntary, thus making the study vulnerable to self-selection bias. Sites that have chosen to participate are likely to have a higher level of environmental awareness and motivation than nonparticipating sites. Consequently, findings may overestimate the ease with which findings could be replicated more broadly. Similarly, the joining fee will limit some sites from being able to participate in the scheme. Whilst most individuals overseeing the management of GreenED are voluntary, resources are required for the RCEM to run the portal and website and cover RCEM quality team time. To improve this, we have approached some governments to ask if they would consider funding the joining fee for sites in a particular country (e.g., Wales) to remove that barrier. The second is the size of the evaluation; 15 sites took part in the accreditation scheme between 2024-2025 from England and Wales, which is relatively small. However, these are sites of different sizes with different demographics, and each site was able to follow the GreenED framework and execute the actions to a satisfactory level for accreditation. We have 49 sites that have signed up for Framework 3.0 in 2026 which will allow us to analyse a far greater collection of data and a more accurate estimation of CO2e and financial savings. Lastly, data collection methods could have been improved. Patient safety and departmental requirements will always come first, and that can make consistent data collection difficult during a busy ED shift; our financial and CO2 predicted savings are all underestimates because of this. Improved data collection systems are being developed for Framework 3.0.

sustainable emergency medicine can elicit rapid decarbonisation and lead to substantial annual financial savings. Applying the guiding principle of ‘Think big, start small, scale quickly’, GreenED has rapidly expanded to provide leadership at an international level. An Australian pilot (13 sites) is in its final stages, and the 2025/26 programme has expanded to Ireland (4 sites), with 32 sites from England and Wales taking part and interest being expressed from EDs in mainland Europe. We are also investigating the feasibility of a modular approach to the frameworks, allowing sites to substitute actions from one level into another to give greater flexibility. We are currently developing GreenED International which we envision being used as an internationally recognised benchmark for environmentally sustainable emergency care in high resource settings. Rapid decarbonisation of healthcare requires that best practices are shared, and we hope that other countries and specialties can use the initiative as a blueprint to adapt and grow environmentally sustainable and resilient healthcare beyond the ED.

Address for Correspondence: Jennifer L. Wood, MBChB, BSc, Victoria Hospital Emergency Department, Hayfield Road, Kirkcaldy, United Kingdom, KY2 5AH. Email: jennifer.wood@ doctors.org.uk. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. JW, AR, TS, FB and ZS all hold voluntary positions in the RCEM Environmental Specialist Interest Group; JW, AR, TS, FB and ZS have all been reimbursed by RCEM for attending emergency medicine conferences to promote GreenED; ZS is paid by RCEM as a project coordinator for GreenED. There are no sources of funding to declare. Copyright: © 2026 Wood et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

REFERENCES

CONCLUSION A systematic and supported approach to environmentally

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1. Watts N, Adger WN, Agnolucci P, et al. Health and climate change: policy responses to protect public health. Lancet. 2015;386:1861-1914. 2. Howard C, MacNeill AJ, Hughes F, et al. Learning to treat the climate emergency together: social tipping interventions by the health community. Lancet Planet Health. 2023;7:e251-264. 3. Salas RN. The climate crisis and clinical practice. N Engl J Med. 2020;382:589-591. 4. NHS England Greener NHS. Delivering a net zero National Health Service. 2020. Available at: https://www.england.nhs.uk/greenernhs/ wp-content/uploads/sites/51/2020/10/delivering-a-net-zero-national-

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Wood et al. health-service.pdf. Accessed March 11, 2026.

and ecological emergency. Br J Gen Pract. 2021;71:439.

5. Health Care Without Harm. Healthcare climate footprint report. 2019.

14. Royal College of Emergency Medicine. GreenED: environmentally

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sustainable emergency medicine. Available at: https://greened.rcem.

climate-footprint-report. Accessed December 5, 2025.

ac.uk. Accessed December 5, 2025.

6. Pichler P, Jaccard I, Weisz U, et al. International comparison of

15. University College London. Laboratory efficiency assessment

health care carbon footprints. Environ Res Lett. 2019;14(6):064004.

framework. Available at: https://www.ucl.ac.uk/sustainable/take-

7. Worrall JC, Hendin A, Kanji S. Just say no to metered dose inhalers.

action/staff-action/leaf-laboratory-efficiency-assessment-framework.

CJEM. 2025;27:317-318.

Accessed December 6, 2025.

8. Azlan NR, Massey D, Andrew L, et al. Time to hang up the gloves: a

16. Kjellström S, Stålne K, Törnblom O. Six ways of understanding

scoping review of evidence on non-sterile glove use during intravenous

leadership development: an exploration of increasing complexity.

antimicrobial preparation and administration. J Adv Nurs. 2025;0:1-17. 9. Socha K, Couffinhal A, Forde I, et al. Tackling wasteful spending on

Leadership. 2020;16(4):434-460. 17. British Medical Association. NHS hospital beds data analysis. 2025.

health. 2017. Available at: https://www.oecd.org/content/dam/oecd/

Available at: https://www.bma.org.uk/advice-and-support/nhs-

en/publications/reports/2017/01/tackling-wasteful-spending-on-

delivery-and-workforce/pressures/nhs-hospital-beds-data-analysis.

health_g1g72f29/9789264266414-en.pdf. Accessed March 11, 2026. 10. Kjelle ER, Andersen AM, Krokeide LJJ, et al. Characterizing and

Accessed March 11, 2026. 18. Jones S, Moulton C, Swift S, et al. Association between delays to

quantifying low-value diagnostic imaging internationally: a scoping

patient admission from the emergency department and all-cause

review. BMC Med Imaging. 2022;22(1). 11. Kotcher J, Maibach E, Miller J, et al. Views of health professionals on

30-day mortality. Emerg Med J. 2022;39:168-173. 19. Royal College of Emergency Medicine. Emergency medicine clinical

climate change and health: a multinational survey study. Lancet

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12. Hunter DJ. At breaking point or already broken? The National Health Service in the United Kingdom. N Engl J Med. 2023;389:100-103.

Accessed March 11, 2026. 20. Holmes S. We can progress sustainable healthcare by breaking silos

13. Kemple T, Smith JN, Sowman G, et al. Primary care and the climate

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and changing behaviours. BMJ. 2024;385:q813.

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Climate Change: Original Research

Evaluating the Impact of a Sustainability Education Intervention on Emergency Medicine Residents Atieh D. Ashkezari, MS* Christina Bogdani* Xueqing Huang, PhD† Michael Gindi, MS, MD*

*New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, Old Westbury, New York † New York Institute of Technology College of Engineering and Computing Sciences, Northern Boulevard, Old Westbury, New York

Section Editor: Shahram Lotfipour, MD, MPH Submission history: Submitted December 1, 2025; Revision received April 12, 2026; Accepted March 30, 2026 Electronically published August 10, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.56998

Introduction: Healthcare is a significant contributor to global greenhouse gas emissions, with emergency departments being among the most resource-intensive settings. Despite increasing awareness of climate change and its health implications, structured sustainability education remains lacking in emergency medicine graduate medical education training. We evaluated the impact of a brief, educational intervention on emergency medicine (EM) residents’ knowledge, attitudes, and self-reported behaviors related to sustainability. Methods: We conducted a prospective pre/post interventional study at two community-based EM residency programs. Emergency medicine residents completed a baseline survey assessing sustainability-related knowledge, attitudes, and self-reported behaviors, followed by a video on sustainable clinical practice and a peer-reviewed paper on the environmental impact of inhalers. Immediate postcourse and one-month follow-up surveys were administered to evaluate short- and intermediate-term changes. Our primary outcome measure was change in sustainability-related knowledge scores. Secondary outcomes included changes in attitudes toward sustainability and selfreported sustainability-related clinical behaviors. Survey responses were analyzed using descriptive statistics, paired t tests and repeated-measures analysis of variance, as appropriate. Results: Of 41 eligible EM residents across two residency programs, 34 completed the baseline survey (82.9%), 28 completed the immediate post-intervention survey (68.3%), and 30 completed the onemonth follow-up survey (73.2%). Knowledge scores at baseline were 55.0% and increased to 68.0% immediately after the intervention (P < .001). At one month, knowledge scores remained higher than baseline (65.0%) (P = .003). Attitudes improved significantly immediately post-intervention (P = .001), despite already neutral-to-positive baseline levels. Two self-reported behavior items improved at one month: preferential prescribing of dry-powder inhalers, which were described in the educational materials as having less of an environmental impact than aerosolized inhalers (12.0% to 37.0%, P < .050) and self-reported efforts to reduce unnecessary waste (56.0% to 87.0%, P < .050), with overall self-reported behavior change (P = .001). Nebulizer-related prescribing did not significantly change. The openended item showed similar thematic patterns at both baseline and after one month, with most residents describing simple waste-reduction actions (eg, minimizing disposables), and no significant shift in qualitative categories. Discussion and Conclusion: A brief, structured sustainability module delivered via a video format was feasible and well-received by EM residents. Preliminary data suggest improvements in knowledge, attitude, and self-reported behaviors, highlighting the potential for scalable sustainability education within graduate medical training. However, these findings should be interpreted in the context of a small sample size and self-reported outcomes. [West J Emerg Med. 2026;27(6.1)132–139.]

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Evaluating the Impact of a Sustainability Education Intervention on EM Residents

INTRODUCTION The healthcare sector accounts for nearly 9% of total greenhouse gas emissions in the United States, with hospitals and clinical care settings representing major contributors due to substantial energy demands and consumption, extensive use of supplies, and significant waste generation.1,2 Among these settings, emergency departments (ED) are particularly resource intensive. They operate continuously and rely heavily on disposable supplies and high-emission clinical processes such as diagnostic imaging, all of which contribute substantially to healthcare-related emissions.3,4 While the relationship between healthcare delivery and climate change has received growing attention in recent years, formalized sustainability training remains limited across undergraduate, graduate, and continuing medical education levels.5 Environmental sustainability in healthcare is increasingly being recognized as a core competency for health professionals.6 Previous studies have highlighted that physicians often lack formal training on how clinical decision-making influences environmental outcomes, including emissions associated with pharmaceuticals, single-use devices, and over-used imaging.7 Quality improvement projects in anesthesia, such as Project SPRUCE, have shown that providing educational modules, clinical decision support, and real-time feedback can lead to substantial reductions in emissions from inhaled anesthetics, with educational interventions being a key driver of sustained practice change.8 However, few published studies have evaluated how sustainability training can be effectively integrated into the fast-paced, high-acuity environment of emergency medicine. A recent perspective from the United Kingdom highlighted growing momentum for sustainable healthcare within EM and outlined actionable strategies to improve environmental practices in EDs, including reducing the use of inhaled agents with high potential for global warming, optimizing waste segregation, and incorporating telemedicine to limit travel-related emissions.9 Despite these developments, a significant gap regarding the integration of formal sustainability training into U.S.based residency programs remains. To address this gap, in this study we evaluated the feasibility of an educational intervention and its impact on EM residents’ knowledge, attitudes, and self-reported behaviors as related to sustainability—delivered via a brief, video-based educational module and a peer-reviewed paper— aimed to provide foundational knowledge on the environmental impact of clinical care and encourage reflection on sustainable practices in the ED.10, 11 Residency training represents a particularly high-leverage opportunity, as it shapes long-term clinical decision-making patterns and practice habits.12 Introducing sustainability concepts at this stage may facilitate early integration of environmentally conscious practices into routine care.

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Population Health Research Capsule What do we already know about this issue? Healthcare contributes significantly to greenhouse gas emissions, yet sustainability education in emergency medicine (EM) training remains limited. What was the research question? Does a brief educational intervention improve EM residents’ sustainability knowledge, attitudes, and behaviors? What was the major finding of the study? Knowledge improved from 55% to 68% immediately post-intervention (P < .001) and remained higher at one month (65%, P = .003). How does this improve population health? Integrating sustainability education into residency training may promote environmentally responsible clinical practices and reduce healthcare-related emissions.

METHODS Study Design and Setting This study was a prospective, single-arm educational intervention conducted across two community hospitals within the same hospital system in New York State. Both sites host accredited EM residency programs that share a common academic structure and didactic schedule. The study was designed to evaluate the impact of a structured sustainability education module on EM residents’ knowledge, attitudes, and self-reported behaviors related to environmentally sustainable clinical practice. Participants All postgraduate year (PGY) 1–3 EM residents scheduled for weekly didactic sessions during the study period were invited to participate. Participation was voluntary, and survey results were anonymous. Only residents present during the assigned educational session were eligible to complete the surveys. No identifying information was collected at any stage of the study. Intervention The intervention consisted of a 60-minute video module, Healthcare Sustainability – Transforming Clinical Practice in the Face of Climate Change, developed by Mass General

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Baseline Survey The baseline survey collected demographics (PGY level, sex, additional academic degrees, and age), 17 knowledge items, eight attitude items, and four behavior items, including one open-ended question regarding personal sustainability practices.

Hospital and publicly available on YouTube10 and an accompanying peer-reviewed paper on the environmental impact of asthma inhalers by Wilkinson and Woodcock.11 Together, these resources provide a comprehensive overview of the environmental impact of healthcare delivery, principles of sustainable clinical decision-making, and practical strategies to reduce waste in EM. For both community hospitals, the intervention was delivered in person without additional facilitation or discussion components to ensure consistency across sites.

Immediate Postintervention Survey The immediate postintervention survey repeated the knowledge and attitude items verbatim from the baseline survey to measure short-term learning gains and attitudinal shifts following the educational module. Behavioral questions were excluded at this stage as meaningful changes in clinical practice behavior require time to develop.

Survey Instrument We developed a structured survey instrument and sent it electronically using REDCap (Research Electronic Data Capture) to assess participants’ knowledge, attitudes, and self-reported behaviors related to environmental sustainability in healthcare. Surveys were distributed at three timepoints: baseline (preintervention); immediate postintervention; and one-month follow-up, with survey content tailored to the intervention’s learning objectives and knowledge-retention assessment at each stage. Each survey began with an eligibility and consent confirmation, requiring participants to verify that they were ≥ 18 years of age and voluntarily agreed to participate. All responses were collected anonymously.

One-Month Follow-Up Survey The one-month survey included brief demographic verification (PGY level and sex) to confirm respondent consistency and repeated the knowledge and behavior domains to assess retention of learning and translation into self-reported clinical practice changes after one-month postintervention. At one month, behavior items, which reflect the downstream application of attitudes, were prioritized over repeating attitudinal questions.

Survey Development and Rationale The survey was developed to target high-yield concepts in clinical sustainability that align with the content of the educational module and with evidence-based practices in healthcare environmental impact. We selected knowledge items to address common areas of limited awareness among clinicians, including the environmental consequences of personal protective equipment selection (Q1); inhaler propellants and prescribing decisions (Q2, Q4–Q6, Q9); sterilization practices and device reprocessing (Q3, Q12, Q13); and the effects of low-value care such as unnecessary imaging or routine testing (Q7, Q14).7 Several questions (Q10, Q15–Q17) were included to contextualize the scale of healthcare-related emissions using widely recognized benchmarks, including the Scope 1–3 framework for measuring an organization’s greenhouse gas emissions in which supply-chain emissions (Scope 3) represent the dominant contributor to healthcare’s carbon footprint.13 Certain items (eg, inhaler-related questions) were simplified for educational purposes and may not have fully captured nuances such as differences between dry-powder and metered-dose inhalers. Attitude items assessed perceived relevance, feasibility, and educational value of sustainability in EM, while behavior items captured prescribing choices, self-reported waste-reduction practices, and personal sustainability strategies. All items underwent content review by faculty members with expertise in EM and sustainability to ensure clarity and alignment with the intervention’s learning objectives. Western Journal of Emergency Medicine

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Scoring We calculated knowledge scores as the percentage of correct responses. Attitude items were summarized using mean Likert values per item, and behavioral responses were reported as categorical frequencies. For graphical visualization, Likert responses (1–5) were converted to a normalized 0–1 scale. Open-ended responses were reviewed qualitatively to identify recurring sustainability themes. Data Collection Surveys were distributed and completed through a REDCap link. The baseline survey was administered immediately prior to the video session, the postintervention survey immediately afterward, and the one-month survey distributed via email reminder. Responses were automatically stored in REDCap and exported for analysis. Statistical Analysis The primary outcome was change in sustainability-related knowledge scores across time points. Secondary outcomes included changes-in-attitude composite scores and selfreported sustainability-related behaviors. All analyses were performed in Python v3.11 (Python Software Foundation, Wilmington, DE). Descriptive statistics were used to summarize demographic data and response distributions. Repeated measures analysis of variance was used to evaluate changes in knowledge across the three time points (baseline, immediate, one month), followed by Bonferroni-adjusted paired t-tests when the omnibus test was significant. Paired

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t-tests were used to compare attitude scores between baseline and immediate post-intervention. Behavioral outcomes measured at baseline and one month were analyzed using paired t-tests and the McNemar test for paired categorical variables. A two-tailed P < .050 was considered statistically significant. Effect sizes (Cohen d) were calculated for primary comparisons to provide estimates of magnitude of change. Ethical Considerations This study was reviewed and approved by the institutional review board (IRB-2026-355) and deemed exempt under educational quality-improvement criteria. Because all data were collected anonymously and no patient-level information was used, separate IRB review by the participating EM training sites was not required. All identifying information was removed to maintain double-blinded peer review per journal requirements. RESULTS Of 41 eligible EM residents across two programs, 34 completed the baseline survey (82.9% response rate), 28 completed the immediate postintervention survey (68.3%), and 30 residents completed the one-month follow-up survey (73.2%), reflecting variation in participation across time points due to attendance and follow-up survey completion. Baseline demographic information, including postgraduate year level, sex, and additional academic degrees, is presented in Table 1. Knowledge Results Seventeen multiple-choice and true/false questions assessed residents’ knowledge of sustainability in healthcare. The mean percentage of correct responses increased from 55.0% at baseline to 68.0% immediately postintervention, corresponding to a large effect size (Cohen d =. 1.048) (Figure

Table 1. Demographic characteristics of emergency medicine residents who completed the baseline survey before participating in a sustainability education intervention in a study of sustainability training. Characteristic PGY level

Gender

Additional degrees

Category

N = 34 (%)

PGY-1

14 (41.2%)

PGY-2

14 (41.2%)

PGY-3

6 (17.6%)

Male

22 (64.7%)

Female

12 (35.3%)

Non-binary / prefer not to say

0 (0.0%)

Yes

14 (41.2%)

20 (58.8%)

PGY, postgraduate year.

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Figure 1. Overall score trends following a brief educational module on sustainable clinical practice delivered in two communitybased emergency medicine residency programs.

1). At the one-month follow-up survey, the average percentage of correct responses was 63.0%, with a similarly large effect size compared to baseline (Cohen d = 0.988), indicating sustained improvement over time. The small negative effect size between immediate and one-month follow-up (Cohen d = −0.253) suggests slight attenuation over time, although the overall effect remained substantial. Detailed item-level data are presented in Supplemental Table S1, and a concise summary of the most notable item-level changes is provided here to contextualize the overall score trends. Across 17 items, several domains demonstrated statistically significant improvements. Notably, significant increases from baseline to immediate postintervention surveys were noted in the knowledge of hospital emission sources (Q10), sterilization hazards (Q12), and the relative magnitude of healthcareassociated pollution harm (Q15) (P < .001, P = .020, and P = .009, respectively), with gains in knowledge maintained at one month in the same three domains (P = .030, P = .010, and P = .040). Awareness of the global ranking of healthcare emissions (Q17) also improved significantly at one month compared with baseline (P = .040). A single item related to life-cycle analysis (Q13) showed a modest decline from immediate to one-month follow-up (P = .050). All other items demonstrated nonsignificant differences across time points (P > .050), indicating stable retention for most concepts. Attitude Results Eight Likert-scale items (1 = strongly disagree to 5 = strongly agree) assessed residents’ attitudes toward sustainability in EM at baseline (N = 34) and immediately postintervention (n = 28). Median scores across all items

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ranged from 3 (“neutral”) to 4 (“agree”), reflecting generally neutral-to-positive attitudes prior to the intervention. When attitude items were averaged into a composite score, residents demonstrated a statistically significant improvement immediately postintervention (P = .001), as shown in Figure 2. Despite this overall increase, item-level analyses did not show statistically significant changes, with most items exhibiting small directional shifts toward greater agreement, particularly regarding the importance of sustainability in clinical care and interest in further learning. Agreement with the negatively worded item assessing perceived impracticality of sustainability in the ED decreased slightly, indicating a modest shift toward lower agreement with the impracticality statement. These item-level findings are presented in Supplementary Table S2. Self-Reported Behavior Results Three self-reported behavior items were assessed at baseline and at the one-month follow-up. A paired t-test comparing overall self-reported behavior scores demonstrated a statistically significant improvement from baseline to one month (P = .001) consistent with the differences illustrated in Figure 3. Two items showed significant change. Residents were more likely to report that they would preferentially prescribe dry-powder inhalers over metered-dose inhalers at one month (12.0% versus 37.0%; P < .050), and significantly more residents reported actively trying to reduce unnecessary waste in their clinical practice (56.0% versus 87.0%; P < .050). No significant change was observed in preferences for prescribing

Figure 2. Shifts in perceptions of the importance, feasibility, and relevance of environmental sustainability in clinical practice among emergency medicine residents.

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Figure 3. Changes in sustainability-related clinical behaviors following a brief educational intervention among 34 emergency medicine residents.

a nebulizer over an inhaler. For the open-ended item, thematic patterns remained stable. “Reduce” was the most common response at both time points (50.0% baseline; 60.0% one month), followed by smaller proportions referencing reuse strategies or describing tension between sustainability and patient care. The proportion of noninformative responses remained unchanged. All behavior results, including thematic frequencies, are summarized in Table 2. DISCUSSION This study evaluated the impact of an educational intervention on EM residents’ knowledge, attitudes, and self-reported behaviors related to environmentally sustainable clinical practice. Sustainability remains largely absent from traditional EM training, despite healthcare’s substantial contribution to greenhouse gas emissions and growing national calls for climate-conscious clinical decision-making.9 Our findings demonstrate that residents’ attitudes toward sustainable practices, while already generally neutral to positive at baseline, showed a significant improvement immediately after the intervention. This attitudinal shift corresponded with meaningful changes in self-reported sustainability-related behaviors at one month. A low-burden, single-session module can meaningfully improve residents’ understanding of key sustainability concepts and influence an intention to change certain practice behaviors, even within the constraints of a busy residency curriculum. Residents demonstrated meaningful improvements in sustainability-related knowledge immediately following the intervention, with overall retention at one month. The strongest gains occurred on question items addressing hospital 136

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Table 2. Item-level self-reported sustainability behaviors at baseline and one-month follow-up of emergency medicine residents after completing a sustainability education module. Question

Behavior item

Baseline % (N = 34)

1-Month % (n = 30)

Significance P < .050

Q.1

Preferentially prescribe DPI over MDI (Yes)

12%

37%

Q.2

Preferentially prescribe nebulizer over inhaler (Yes)

26%

40%

Q.3

Actively try to reduce unnecessary waste (Yes)

56%

87%

P < .050

Q.4

Sustainability practices (open-ended) •

Reduce

50%

60%

•

Reuse/Recycle

12%

•

Tension/Impact on patient care

29%

33%

• Not Informative DPI, dry-powder inhaler; MDI, metered-dose inhaler; ns, nonsignificant.

emission sources, sterilization safety, and healthcare’s contribution to pollution, concepts that are rarely emphasized in EM training and are generally unfamiliar to clinicians.4 These findings suggest that brief, structured instruction can effectively close foundational knowledge gaps, particularly in domains lacking clinical exposure or experiential reinforcement. The question item addressing the understanding of Scope 3 emissions—the indirect, supplychain emissions that make up most of the healthcare’s carbon footprint—also improved.13 In contrast, Scope 1 (direct emissions from onsite fuel use) and Scope 2 (indirect emissions from purchased electricity) represent a much smaller share of total healthcare emissions.13 Notably, increased awareness of the disproportionate impact of Scope 3 emissions is particularly relevant to everyday decision-making in the ED, where equipment, pharmaceuticals, and disposables contribute to the overall environmental impact. Knowledge gains that persisted at one month further support the durability of the intervention and reinforce the value of integrating sustainability content into formal resident education. Residents’ attitudes toward sustainability were generally neutral to positive at baseline, typically 3–4 on a five-point Likert scale and demonstrated a statistically significant improvement immediately postintervention. Although the median Likert values shifted only modestly, the paired statistical comparison showed consistent upward movement across multiple attitude items, reflecting a meaningful attitudinal shift despite a relatively high baseline starting point. Such ceiling effects can partially mask visible changes and limit the measurable impact of a single educational exposure, particularly when learners already agree with the underlying concepts. Prior research consistently shows shifting attitudes to be more resistant to change than improving knowledge or self-reported behaviors, often requiring repeated reinforcement, hands-on experience, or institutional cues to produce measurable movement.14 The Volume 27, Supplement: November 2026

n.s.

small directional shifts toward greater agreement, particularly regarding the importance of sustainable practice and the desire to learn more, may suggest ongoing receptivity and potential for cumulative change with repeated or more immersive educational touchpoints. Self-reported behaviors were also evaluated in this study. Two of the three self-reported behavior items demonstrated significant improvement at one month, underscoring the practical impact of the intervention. Residents became more likely to preferentially prescribe dry-powder inhalers over metered-dose inhalers and more frequently reported actively attempting to reduce unnecessary waste in their clinical practice. These findings reflect shifts in clinical practice, highlighting the importance of education and its ability to translate into modifiable and actionable habits. The lack of change in nebulizer versus inhaler prescribing is unsurprising, as this decision is typically driven by patient acuity, airway dynamics, and institutional protocols rather than physician preference.15 Overall, the observed behavior changes suggest that brief, targeted education can influence day-to-day decision-making in the ED, even in the absence of broader structural or policy modifications. These findings align with emerging literature demonstrating that targeted educational interventions can improve sustainability-related knowledge and clinical decision-making in other specialties, particularly anesthesia and perioperative care.16 Prior initiatives, such as the adoption of low–global warming potential anesthetic agents or wastereduction programs in operating rooms, have similarly shown that clinicians respond positively to structured, evidence-based sustainability training.17 However, published data within EM remains limited. Existing literature consists largely of conceptual reviews, case examples, and proposed frameworks rather than evaluated interventions with measurable outcomes, as reflected in prior reviews identifying a gap in the EM evidence base and calling for further research to inform

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Evaluating the Impact of a Sustainability Education Intervention on EM Residents practice.9 By providing quantitative evidence that a brief, scalable module can meaningfully improve knowledge, enhance EM residents’ attitudes toward sustainable healthcare, and influence practice behaviors among them, this study fills an important gap and supports the feasibility of incorporating sustainability education into routine residency training. The observed improvements in knowledge, attitude and the reported practice behaviors of residents highlight the feasibility of integrating sustainability content into EM education with minimal disruption to existing curricula. Because the intervention used freely available, asynchronous materials, it represents a low-cost and easily scalable approach that residency programs can adopt as part of didactics, onboarding, or annual competency training. The findings also underscore the potential for sustainability principles to become embedded within routine clinical decision-making when learners are provided with clear, actionable guidance. As hospitals increasingly aim to reduce their environmental footprint, aligning resident education with institutional sustainability initiatives may further reinforce behavior change and promote a consistent culture of resource stewardship across emergency care settings. LIMITATIONS This study has several limitations. It was conducted within a single hospital system, which may limit generalizability to other EM programs with different resources, workflows, or institutional cultures. Participation was based on attendance at scheduled didactics, creating potential selection bias and modest sample sizes at each time point. Although response rates were modest, this is consistent with survey-based research among medical trainees. Importantly, response rate alone does not necessarily indicate nonresponse bias, as nonresponse bias depends on whether the characteristics or opinions of nonrespondents differ meaningfully from those of respondents. Prior work has demonstrated that response rate and nonresponse bias are related but distinct constructs and that low response rates do not inherently invalidate survey findings in medical education research.18 Sex-stratified analyses were not performed because differences by sex were not hypothesized; however, the study included both male and female residents. Behavioral outcomes were self-reported and may not fully reflect objective practice patterns. The survey instrument was developed for this project and was not previously validated, which may limit the precision and interpretability of the knowledge, attitude, and behavior measures. Additionally, the one-month follow-up period limits insight into long-term retention or sustained self-reported behavior change. Furthermore, the intervention consisted of a single, standalone video module and a peer-reviewed paper without facilitated discussion or reinforcement, which may explain the modest improvement of attitude scores and highlight the need for more longitudinal curricula. Despite these limitations, the Western Journal of Emergency Medicine

Ashkezari et al.

study provides early, quantitative evidence supporting the feasibility of sustainability-focused education in EM. CONCLUSION A brief educational intervention was associated with improvements in emergency medicine residents’ knowledge of healthcare sustainability, strengthened their attitudes toward environmentally responsible clinical care, and influenced key self-reported clinical behaviors. These findings demonstrate that sustainability education can be feasibly integrated into existing residency training using low-cost, scalable materials. As healthcare systems increasingly pursue environmental accountability, incorporating structured sustainability curricula into EM training may help prepare future clinicians to make informed, environmentally conscious decisions in everyday practice. Future studies should evaluate multicenter implementation, objective measures of behavior change, and the impact of repeated or longitudinal educational exposure. ACKNOWLEDGMENTS We thank the emergency medicine residents who participated in this study for their time and commitment. We are also grateful to the residency program directors and departmental leaderships for their support in implementing the educational intervention and facilitating study logistics.

Address for Correspondence: Atieh D. Ashkezari, MS, New York Institute of Technology College of Osteopathic Medicine, Northern Boulevard, Old Westbury, NY 11568. Email: adehgh02@nyit.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Ashkezari et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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1. Pohl H, de Latour R, Reuben A, et al. GI multisociety strategic plan on environmental sustainability. Gastrointest Endosc. 2022;96(6):881-886.e2. 2. Dolcini M, Ferrè F, Brambilla A, et al. Integrating environmental sustainability into hospitals performance management systems: a scoping review. BMC Health Serv Res. 2025;25(1):764. 3. American College of Emergency Physicians. Emergency department planning and resource guidelines. Policy statement. Ann Emerg Med. 2014;64(5):564-572. 4. Linstadt H, Collins A, Slutzman JE, et al. The climate-smart emergency

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department: a primer. Ann Emerg Med. 2020;76(2):155-167.

12. Sirovich BE, Lipner RS, Johnston M, et al. The association between

5. Ghosh AK, Azan A, Basu G, et al. Building climate change into

residency training and internists’ ability to practice conservative-

medical education: a Society of General Internal Medicine position

ly. JAMA Intern Med. 2014;174(10):1640-1648.

statement. J Gen Intern Med. 2024;39(13):2581-2589.

13. Rodríguez-Jiménez L, Romero-Martín M, Spruell T, et al. The carbon

6. Tun S. Fulfilling a new obligation: teaching and learning of sustain-

footprint of healthcare settings: a systematic review. J Adv Nurs.

able healthcare in the medical education curriculum. Med Teach.

2023;79(8):2830-2844.

2019;41(10):1168-1177.

14. Davis D, O’Brien MAT, Freemantle N, et al. Impact of formal

7. Lynch M, McCaffery K, Barratt A, et al. Australian and Canadian

continuing medical education: do conferences, workshops, rounds,

clinicians’ views and application of ‘carbon health literacy’: a

and other traditional continuing education activities change physician

qualitative study. BMC Health Serv Res. 2024;24(1):1457.

behavior or health care outcomes? JAMA. 1999;282(9):867-874.

8. Hansen EE, Chiem JL, Righter-Foss K, et al. Project SPRUCE:

15. Pedersen S. Inhalers and nebulizers: which to choose and

saving our planet by reducing carbon emissions, a pediatric

why. Respir Med. 1996;90(2):69-77.

anesthesia sustainability quality improvement initiative. Anesth Analg.

16. Chambrin C, de Souza S, Gariel C, et al. Association between

2023;137(1):98-107.

anesthesia provider education and carbon footprint related to the

9. Spruell T, Webb H, Steley Z, et al. Environmentally sustainable

use of inhaled halogenated anesthetics. Anesth Analg.

emergency medicine. Emerg Med J. 2021;38(4):315-318. 10. Massachusetts General Hospital. Healthcare sustainability: trans-

2023;136(1):101-110. 17. Dölker T, Schuler J, Wallqvist J, et al. Easy-to-implement educational

forming clinical practice in the face of climate change. YouTube.

interventions to bring climate-smart actions to daily anesthesiologic

2024. Available at: https://youtu.be/4uB0MujR_V4. Accessed August

practice: a cross-sectional before and after study. Minerva Anestesiol.

3, 2025.

2024;90(3):126-134.

11. Wilkinson A, Woodcock A. The environmental impact of inhalers for

18. Phillips AW, Reddy S, Durning SJ. Improving response rates and

asthma: a green challenge and a golden opportunity. Br J Clin

evaluating nonresponse bias in surveys: AMEE guide No. 102. Med

Pharmacol. 2022;88(7):3016-3022.

Teach. 2016;38(3):217-228.

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Western Journal of Emergency Medicine

Climate Change: Original Research

Climate Change and Heat-related Illness in Older Adults: Implications for Emergency Medicine Erin L. Simon, DO* Kevin Watkins, MD* Stephen Meldon, MD†

*Cleveland Clinic Akron General, Department of Emergency Medicine, Akron, Ohio † Cleveland Clinic, Department of Emergency Medicine, Cleveland, Ohio

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted November 18, 2025; Revision received April 12, 2026; Accepted March 30, 2026 Electronically published August 17, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.54008

Climate change is increasing the frequency, duration, and intensity of extreme heat events, creating a growing public health threat for older adults. Age-related physiologic decline, comorbid chronic diseases, polypharmacy, and social vulnerability all contribute to reduced heat tolerance and higher rates of heat-related morbidity and mortality. Emergency departments (ED) are increasingly encountering older adults presenting with minor heat illness, heat stroke, and exacerbations of chronic illnesses triggered by heat exposure. This review synthesizes current evidence describing why older adults are disproportionately affected by extreme heat, highlights key social and environmental determinants of vulnerability, and outlines clinical and public health strategies that emergency clinicians and EDs can assist with to reduce risk. As global temperatures rise, proactive prevention, early recognition, and coordinated community interventions are essential to protect this high-risk population. [West J Emerg Med. 2026;27(6.1)140–144.]

INTRODUCTION Climate change has led to a rise of 1.5 ºC in mean global temperature since the Industrial Revolution, with projected increases of 2.5-2.9 ºC by the end of this century1 and is accelerating the burden of heat-related illness worldwide, with older adults among the most affected. Rising average temperatures and more frequent, severe, and prolonged heat waves have led to marked increases in heat-related morbidity and mortality. The majority of deaths due to heat waves globally are in those > 65 years of age.2 In adults ≥ 65 years, heat-related deaths have risen by more than 50% in the past two decades, with climate change accounting for a substantial share of warm-season mortality.3,4 In the United States, those > 65 years of age account for 40% of all heat-related deaths.5 In addition, older individuals are likely to constitute a higher percentage of the population, with those at least 69 years old projected to increase from 11% in 2024 to 17% in 2050. This population is particularly concentrated in the Northeast, Midwest, and South Atlantic. Shared socioeconomic pathways are climate-population scenarios used to project how demographic change, economic development, and inequality may influence future heat exposure and health risk.6 In this context, these models suggest that older adults, particularly those with medical comorbidity, limited Western Journal of Emergency Medicine

resources, or reduced access to cooling, will face progressively greater heat exposure and heat-related health consequences over time.4,7-10 For emergency clinicians, the relevance of these models is that they anticipate a growing number of older adults at risk for heat-related illness and heat-triggered exacerbations of chronic disease, underscoring the need for improved recognition, prevention, and systems-level preparedness.11 Older adults face unique vulnerabilities due to impaired thermoregulation, higher rates of chronic disease, polypharmacy, and use of medications that impair heat dissipation, reduced physiologic reserve, and social factors such as isolation mobility issues that limit access to cooling resources.12,13 The emergency department (ED) is often the first point of contact for patients experiencing heat-related illness or exacerbations of heatsensitive conditions. This review summarizes the physiologic, pharmacological, environmental, and social contributors to heat vulnerability in older adults and provides guidance for emergency clinicians caring for this growing at-risk population. PHYSIOLOGIC AND PHARMACOLOGIC VULNERABILITY OF OLDER ADULTS Aging significantly reduces the body’s ability to thermoregulate. Older adults experience diminished sweat

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Simon et al. production, reduced skin blood flow, impaired cardiovascular responses, and decreased renal concentrating ability, all of which contribute to heat retention.14,15 Additionally, older adults underestimate their vulnerability to extreme heat.15 Comorbidities common in older age, such as cardiovascular disease, diabetes, chronic kidney disease, chronic respiratory illness, obesity, and dementia, further limit thermoregulatory efficiency and increase the risk of dehydration, hypotension, and organ dysfunction during heat exposure.13,16 Heat exposure not only causes classic heat-related illnesses but also exacerbates underlying chronic conditions, such as diabetes, hypertension, chronic kidney disease, and cardiovascular disease, increasing the risk of hospitalization and death. Studies consistently report an increase in cardiovascular and respiratory mortality in elderly persons during hot days.17 Polypharmacy is another major driver of vulnerability. Frequently prescribed medications, including diuretics, beta-blockers, calcium channel blockers, anticholinergics, antipsychotics, antihistamines, and antidepressants, can impair sweating, alter fluid balance, blunt cardiovascular compensation, or affect cognitive awareness, thereby increasing susceptibility to heat-related illness.8,18-21 Taken together, age-related physiologic decline, chronic medical conditions, and medication effects substantially elevate the risk of heat exhaustion, heat stroke, and decompensation of existing illnesses during extreme heat events. Key physiologic changes and medication classes that increase heat vulnerability in older adults are summarized in Table 1.

effective prevention and targeted outreach during heat waves.

ENVIRONMENTAL AND SOCIAL DETERMINANTS OF HEAT VULNERABILITY Heat risk in older adults is strongly shaped by environmental, demographic, and socioeconomic factors. Individuals living in poverty or on fixed income, in older housing without air conditioning, or neighborhoods with dense infrastructure and minimal green space (known as urban heat islands) face disproportionate exposure to extreme heat.5,19 Additionally, older Americans living in northern cities may be particularly vulnerable to the effects of heat waves due to the relative lack of acclimatization and air conditioning.22 Geographic “hotspots” where older Americans may be sensitive are the deep South and upper Midwest.11 Social isolation, limited mobility, and lack of access to transportation or community cooling centers further increase vulnerability; in fact, isolation has been identified as a key risk factor for death during extreme heat events.23 Those living in isolation, especially with cognitive impairments, may not receive or understand the severity of emergency information. Marginalized racial and ethnic groups face additional risk due to structural inequities, including limited access to healthcare, fewer cooling resources, and residence in hotter urban microclimates.8 These intersecting vulnerabilities amplify the likelihood of heat-related hospitalizations and deaths in older populations. Recognizing these social and environmental risks is essential for

CLINICAL IMPLICATIONS FOR EMERGENCY MEDICINE Clinical implications of extreme heat for emergency medicine include both system- and department-level, and patient-level considerations. Associations between extreme heat events and increases in ED visits and hospitalization are well documented. One study noted an increase of nearly 8% in the relative risk for ED visits for any cause, equating to 24 excess visits per 100,000 persons at risk per day.24 An analysis of approximately 50 million summertime admissions showed an increased rate of admission correlating to increases in daily maximum heat index across the U.S.25 Mortality also increases with significant heat events, with high ambient temperatures and multiple heat waves causing an estimated 61,000 heat-related deaths in Europe in 2022.26 Clinically, older adults often present with atypical or subtle manifestations of heat-related illness. Confusion, weakness, decreased oral intake, falls, syncope, or worsening of chronic conditions may precede classic symptoms such as hyperthermia or anhidrosis; additionally, classically described features, such as anhidrosis, are not always present. The symptoms often overlap with or occur simultaneously with other common conditions, such as sepsis. During heat waves, emergency physicians should maintain a high index of suspicion, particularly in patients with known comorbidities or those taking heat-sensitive medications that increase the risk of heat illness.

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Population Health Research Capsule What do we already know about this issue? Older adults account for most heat-related deaths due to impaired thermoregulation, chronic disease, medications, and social vulnerability. What was the research question? Why are older adults especially vulnerable to extreme heat, and what can EDs do to reduce risk? What was the major finding of the study? Heat-related deaths in adults ≥65 years increased >50% over two decades. How does this improve population health? Identifies prevention, early recognition, and community interventions to reduce heat-related illness and death in older adults.

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Table 1. Physiologic and pharmacologic factors contributing to heat vulnerability in older adults. Category Physiologic factors

Pharmacologic factors

Factor Diminished sweat production

Mechanism Reduced evaporative cooling

Emergency medicine relevance Higher risk of heat retention and delayed heat dissipation

Reduced skin blood flow Impaired peripheral vasodilation limits heat transfer to skin

Less effective thermoregulation during heat exposure

Impaired cardiovascular response

Reduced cardiac reserve limits circulatory compensation

Greater risk of hypotension, syncope, and decompensation

Decreased renal concentrating ability

Reduced ability to conserve water and maintain fluid balance

Increased risk of dehydration, electrolyte abnormalities, and acute kidney injury

Reduced physiologic reserve

Lower tolerance for thermal stress

More rapid deterioration with modest heat exposure

Chronic comorbid disease

Cardiovascular, metabolic, renal, pulmonary, and cognitive disease may impair adaptation to heat

Higher risk of atypical presentation, delayed recognition, and worse outcomes

Diuretics

Increase fluid loss and electrolyte derangements

Higher risk of dehydration, hypotension, and acute kidney injury

Beta-blockers

Blunt cardiovascular compensation

Reduced physiologic response to heat stress

Calcium channel blockers

May impair hemodynamic adaptation

Possible worsening of heat-related instability

Anticholinergics

Decrease sweating

Impaired heat dissipation and greater overheating risk

Antipsychotics

Disrupt thermoregulation and cognition

Delayed recognition and more severe presentation

Antihistamines

May impair sweating and cause sedation

Reduced symptom awareness and heat tolerance

Antidepressants

May alter sweating, cognition, or fluid balance

May contribute to subtle or mixed presentations

Rapid assessment, including accurate core temperature measurement and prompt management such as active cooling, volume resuscitation, electrolyte correction, and careful review of medications, are critical to preventing progression to heat stroke and multiorgan dysfunction. Acute mild and moderate heatrelated illnesses include heat rash (pruritic papules resulting from blocked eccrine sweat glands), heat cramps (painful involuntary muscle cramping resulting from sweating-induced dehydration and electrolyte imbalances), heat edema (which may occur in the hands and feet), heat syncope (generally associated with prolonged standing or a change to a standing position in the setting of hot temperatures), and heat exhaustion. Heat exhaustion typically presents as weakness, dizziness, nausea, headache, and muscle cramps, with heavy sweating and rapid pulse evident; the core body temperature may be elevated, but mental status remains normal. Heat stroke is a severe form of heat illness, in contrast to heat exhaustion, involves alterations in central nervous system functioning in association with a core body temperature exceeding 40 °C. Heat stroke is a true medical emergency and can rapidly progress to multiorgan failure and death. Recent clinical reviews provide an excellent summation of the full spectrum of heatWestern Journal of Emergency Medicine

related illnesses, associated medications effects, and evidencebased treatment approaches.3,18 The clinical presentation and treatment of heat illness, from mild heat edema and heat syncope to heat exhaustion and the more severe heat stroke, should be familiar to all emergency clinicians. Emergency clinicians also play a role in prevention by educating patients and caregivers, identifying those at risk for recurrent heat-related illness, and coordinating with outpatient clinicians and community resources. Emergency physicians can specifically provide information on cooling centers and discuss the risks and benefits of certain medications during heat waves. Common and atypical presentations of heat-related illness in older adults, along with a high-level emergency department approach, are summarized in Table 2. PREVENTION AND PUBLIC HEALTH STRATEGIES Heat-related illnesses in older adults are highly preventable. Effective strategies include anticipatory guidance before heat waves, early warning systems, accessible cooling centers, home air-conditioning assistance, and social outreach programs that check on isolated older adults during periods of extreme heat.16,19,20

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Table 2. Heat-related illness in older adults: common presentations and emergency department approach. Category

Typical features in older adults

Emergency department approach

Atypical early presentation

Confusion, weakness, decreased oral intake, Maintain high suspicion during heat events, especially in falls, syncope, or worsening of chronic disease; patients with comorbidities or heat-sensitive medications; classic findings such as anhidrosis may be absent obtain accurate core temperature and assess volume status, electrolytes, and end-organ injury

Heat rash / heat edema / heat cramps

Pruritic rash, dependent swelling, painful muscle cramping

Supportive care, cooling, oral or IV hydration as needed, and correction of electrolyte abnormalities

Heat syncope

Brief loss of consciousness or presyncope, often after prolonged standing or abrupt standing in hot conditions

Supine positioning, cooling, hydration, and evaluation for alternative or concurrent causes of syncope

Heat exhaustion

Weakness, dizziness, nausea, headache, muscle cramps, heavy sweating, tachycardia; temperature may be elevated, but mental status remains normal

Remove from heat, active cooling, fluid resuscitation, electrolyte correction, medication review, and reassessment for progression

Heat stroke

Core temperature typically > 40 °C with altered mental status or other CNS dysfunction; may rapidly progress to multiorgan failure

Immediate emergency treatment with rapid cooling, aggressive supportive care, resuscitation, and close monitoring for organ dysfunction

Exacerbation of chronic illness

Decompensation of cardiovascular, renal, respiratory, or metabolic disease during heat exposure

Evaluate for concurrent heat-related illness while treating the underlying exacerbation; review contributing medications and disposition carefully

Disposition and prevention

Older adults may remain vulnerable after apparent stabilization

Provide counseling on hydration, medication risks, early symptoms, and avoidance of peak heat; connect patients and caregivers with cooling centers and community resources

CNS, central nervous system; IV, intravenous.

Clinicians can help reduce risk by reviewing medications during hot weather, encouraging adequate hydration, promoting awareness of early heat illness symptoms, and advising patients to avoid outdoor or strenuous activities during peak heat hours. In addition, media interviews with emergency clinicians are a frequent request during heat spells and can be effective at reaching older audiences over a large local area. Furthermore, emergency physicians can provide knowledge of local resources, such as location of cooling centers, during heat waves. Partnerships between EDs, public health agencies, emergency medical services, and community organizations are essential to building climate resilience and protecting vulnerable older adults. CONCLUSION Older adults face disproportionate and growing risks from climate change-related heat exposure. Physiologic decline, chronic medical illness, medication effects, and social vulnerability all contribute to increased susceptibility to heat-related morbidity and mortality. Emergency clinicians are uniquely positioned to recognize at-risk individuals, initiate timely management, and support prevention efforts. As climate change accelerates, integrating heat-risk awareness into emergency care and collaborating with public health systems will be crucial to safeguarding the health of the growing demographic of older adults. Volume 27, Supplement: November 2026

Address for Correspondence: Erin Simon, DO, Cleveland Clinic Akron General, Department of Emergency Medicine, 1 Akron General Ave, Akron, OH 44307. Email: esimon78@yahoo.com. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Simon et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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review and meta-analysis. Sci Total Environ. 2022;852:158332.

of emergency department visits among adults in the United States:

13. Meade RD, Akerman AP, Notley SR, et al. Physiological factors characterizing heat-vulnerable older adults: a narrative review.

time stratified case crossover study. BMJ. 2021;375:e065653. 25. Vaidyanathan A, Saha S, Vicedo-Cabrera AM, et al. Assessment of

Environ Int. 2020;144:105909.

extreme heat and hospitalizations to inform early warning systems.

14. Meade RD, Notley SR, Akerman AP, et al. Physiological responses

Proc Natl Acad Sci U S A. 2019;116(12):5420-5427.

to 9 hours of heat exposure in young and older adults. Part I: body

26. Ballester J, Quijal-Zamorano M, Méndez Turrubiates RF, et al. Heat-

temperature and hemodynamic regulation. J Appl Physiol (1985).

related mortality in Europe during the summer of 2022. Nat Med.

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Climate Change: Original Research

Implementation Science to Advance Equity in Climate-Driven Disaster Response William Mundo, MD, MPH*† Jessica Ryder, MD* Madeline Ross, MD, MPH* Corey B. Bills, MD, MPH* Lee S. Newman, MD, MA†‡§ Jay Lemery, MD*

*University of Colorado School of Medicine, Department of Emergency Medicine, Aurora, Colorado † University of Colorado Anschutz Campus, Colorado School of Public Health, Department of Environmental and Occupational Health, Aurora, Colorado ‡ University of Colorado Anschutz Campus, Colorado School of Public Health, Centers for Health Work and Environment, Aurora, Colorado § University of Colorado Anschutz Campus, School of Medicine, Department of Medicine, Division of Pulmonary Sciences and Critical Care Medicine, Aurora, Colorado

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted November 4, 2025; Revision received April 4, 2026; Accepted March 30, 2026 Electronically published August 10, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.53809

Climate hazards are causing increasingly frequent and severe disasters. The populations most impacted by the health and social costs of disasters include language minorities, displaced individuals, and low-income communities. This commentary explores three key issues. First, climate hazards lead to displacement and increase vulnerability by disrupting housing, livelihoods, and access to care. Second, current emergency and disaster frameworks often overlook equity in communication, access to care, and recovery. Third, practical solutions can prioritize equity across mitigation, preparedness, response, and recovery. We review evidence on climate displacement, legal protections, and the roles of the health system. We highlight recurring operational opportunities, such as language access, navigation barriers, and fragmented recovery efforts. We also propose feasible strategies aligned with implementation science, including multilingual warning systems, interpreter-ready triage, mobile clinics, community health worker networks, simplified recovery navigation, and policy changes to reduce documentation barriers. This commentary aims to help emergency leaders, public health agencies, and community partners turn intentions into measurable, sustainable equity improvements. Prioritizing language access and legal realities in disaster planning can reduce preventable health issues and accelerate recovery for groups most affected by climate change. [West J Emerg Med. 2026;27(6.1)145–154.]

INTRODUCTION Climate change acts as a threat multiplier. It accelerates global temperature rise and increases the frequency, severity, and unpredictability of climate-driven hazards with a disproportionate impact on language minority, immigrant, and low-income populations (Table 1).1–7 Elevated risks of morbidity stem from structural vulnerabilities, such as substandard housing and limited access to health care, often worsened by pre-existing medical conditions, all of which increase exposure to disasters, escalate health impacts, and diminish recovery capacity.8,9 The Global South and Volume 27, Supplement: November 2026

underserved populations in high-income countries face amplified physical health burdens and mental health strains postdisaster, worsened by environmental injustice and weak adaptive infrastructure.10–12 Without deliberate, equity-centered adaptation, the climate may amplify health inequities and deepen systemic vulnerabilities as extreme weather intensifies. The human toll of increased frequency and severity of disasters is not shared equally. International standards, such as the United Nations (UN) Guiding Principles on Internal Displacement and the Global Compact for Safe, Orderly, and Regular Migration, affirm the right to protection and 145

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nondiscrimination in humanitarian response.13 Despite these commitments, many international and domestic disaster management systems lack explicit operational safeguards to ensure equity in communication, shelter access, medical care, and long-term recovery support.14–18 Existing policies often address vulnerability in general terms but fail to account for the intersecting effects of language, displaced status, and socioeconomic marginalization. This commentary aims to discuss how climate change drives displacement and entrenches vulnerability, identify structural inequities within current disaster systems, and explore scalable, equity-focused innovations for preparedness, response, and recovery. In this commentary, “language minority” refers to populations whose preferred language differs from that of the dominant social group, including those with limited English proficiency and multilingual communities worldwide. The term “displaced people” includes both refugees who cross international borders and internally displaced persons who remain within their country of origin. Finally, “climate migrants” are those forced to move due to environmental changes that make their home regions uninhabitable or unsafe. While our discussions draw examples from both global and United States (U.S.) contexts, the analysis centers on lessons relevant to emergency medicine, public health, and policy leaders who design or implement disaster response systems. This commentary seeks to inform a cross-disciplinary audience on how implementation science can strengthen equity across all phases of climate-related disaster preparedness and response by bridging humanitarian definitions with operational realities. CLIMATE AND DISPLACEMENT Climate-related disasters are no longer seasonal anomalies but recurring crises that erode community resilience and cause large-scale displacement. According to the Internal Displacement Monitoring Centre, sudden-onset weather events internally displaced more than 26.4 million people within their countries in 2023 alone, and projections from the World Bank suggest that by 2050, over 216 million people could be forced to move within their countries due to climaterelated impacts.19–21 Rising sea levels, for example, are gradually making coastal areas uninhabitable and threatening entire island nations, while persistent droughts, aridity, and intensifying wildfire seasons are displacing millions globally and in the U.S.22–24 Drought also fuels both rural depopulation and political instability, and extreme storms trigger mass evacuations.25,26 This sustained and repeated displacement creates prolonged recovery cycles, destabilizes local economies, and undermines long-term adaptation capacity, making climate-linked migration one of the defining humanitarian and policy challenges of this century. Structural inequities in housing, labor, and access to services often place low-income, at-risk of displacement, and language minority populations in areas most exposed to Western Journal of Emergency Medicine

Population Health Research Capsule What do we already know about this issue? Climate disasters disproportionately harm language minority, displaced, and low-income communities, yet equity remains inconsistently integrated into disaster response. What was the research question? How can implementation science help build more equitable climate disaster preparedness, response, and recovery? What was the major finding of the study? PRISM and RE-AIM offer a practical framework to integrate equity into disaster planning and implementation. How does this improve population health? An implementation science approach may strengthen equitable disaster systems by improving communication, access to care, and recovery for vulnerable populations.

environmental risk.12 For example, dense urban areas often amplify heat exposure via the urban heat island effect.27 At the same time, low-lying coastal or floodplain housing is subject to recurring inundation and storm damage.28–30 These communities are further disadvantaged by limited adaptive capacity, including inadequate insurance coverage, limited financial reserves, and restricted mobility, all of which can prolong postdisaster hardship during both evacuation and recovery.12 These patterns reveal that vulnerability is socially produced and geographically reinforced. Building equitable climate adaptation through resilient infrastructure, affordable housing reform, and targeted disaster planning is, therefore, a core public health priority. Displacement disrupts nearly every dimension of health and social stability. It breaks continuity of care, medication access, mental health stability, and social bonds, especially in communities already facing systemic barriers and low trust in institutions. The loss of consistent health care is especially damaging for individuals managing chronic diseases such as diabetes, asthma, and hypertension, conditions that often worsen after disasters.31,32 The trauma of losing a home or loved one is intensified by secondary trauma from navigating unfamiliar systems, dealing with xenophobia or racism, and confronting restrictive health care policies.33–35 For children, forced relocation interrupts education and mental health support and destabilizes their development during crucial years, leading to long-term health and psychosocial issues.36,37 The loss of

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Mundo et al. Table 1. Climate-driven hazards and impacts. Hazard

Description

Proximal Impact (Direct or Individual)

Distal Impact (Indirect or Structural)

Sea-level rise

Coastal inundation, freshwater contamination, and salinization of freshwater.

Injuries from flooding, diarrheal disease from water contamination, and mental health disorders from displacement.

Permanent loss of habitable land, displacement of communities with no relocation resources, cultural erasure, long-term livelihood collapse (fishing, coastal farming), and intergenerational trauma.

Extreme weather events

Intensified hurricanes, Physical trauma (burns, drowning, crush Housing insecurity, economic destabilization, floods, and wildfires. injuries), acute respiratory illness, disrupted education systems, and cycles of infectious disease outbreaks, PTSD, poverty are tied to recurrent disaster exposure. and depression exacerbation.

Drought and desertification

Persistent water Acute malnutrition, dehydration, scarcity, soil, and land diarrheal illness, vector-borne degradation. outbreaks, and mental health impacts from food insecurity

Food insecurity and forced migration among subsistence farmers, as well as economic collapse in communities reliant on informal labor, are linked to declines in farming, fishing, and herding.

Environmental Air quality, drought, Heat illness, asthma/COPD Long-term biodiversity-driven nutritional decline degradation aridity, soil erosion, exacerbations, cardiovascular events, and reduced adaptive capacity of health care water quality/scarcity, and mental health disorders are linked systems. and biodiversity loss. to chronic exposures. COPD, chronic obstructive pulmonary disease; PTSD, post-traumatic stress disorder.

familiar networks and community supports weakens social cohesion, a critical factor for recovery and resilience.38,39 Workers exposed to climate extremes, including agricultural and construction laborers, experience heat stress, unsafe conditions, and income loss.40 These intersecting disruptions reveal how displacement extends beyond physical dislocation; it fractures systems of care, livelihoods, and trust. Strengthening trauma-informed, culturally responsive health and social services within disaster planning frameworks is essential to protect displaced individuals and rebuild resilient communities. Climate migrants are individuals forced to relocate because of climate-related events that make their home environments unsafe or uninhabitable.41 Policymakers increasingly recognize this population as one of the fastestgrowing groups of displaced people worldwide. At the end of 2024, 123.2 million people worldwide had been forcibly displaced by conflict, persecution, or events that disturb public order; of these, 42.7 million were refugees who crossed borders, while 73.5 million were internally displaced persons who remained inside their own countries.42 The predominance of internal displacement emphasizes that most displaced individuals travel short distances rather than crossing borders. Because international refugee law applies only to those displaced by persecution or conflict, not environmental change, internally displaced climate migrants often lack the legal recognition and access to international protection given to refugees. These distinctions highlight a critical policy gap that will influence future humanitarian and health equity responses to climate-driven migration. Currently, there is no binding international legal recognition or protection for climate refugees (Table 2).43–51 Under existing law, the 1951 Refugee Convention does not Volume 27, Supplement: November 2026

cover those displaced solely by environmental factors, leaving externally displaced climate migrants in a legal void.52,53 Some frameworks, such as the UN Global Compact for Migration, the Sendai Framework for Disaster Risk Reduction, and the Guiding Principles on Internal Displacement, provide soft-law guidance, but they lack enforceable rights and obligations.54,55 Climate-related disasters are one of the main drivers of internally displaced persons, forcing individuals to move within their own borders in search of safety.56 Internally displaced persons often lose homes, livelihoods, and access to care while remaining outside the scope of international refugee protections. The UN High Commissioner for Refugees (UNHCR) climate action framework emphasizes that national governments must strengthen resilience, protect rights, and integrate climate displacement into disaster risk reduction and humanitarian response planning.57 Proposed solutions include expanding the definition of refugees to include climate displacement, creating a dedicated climate migration treaty, or embedding protections within human rights frameworks.58,59 However, these proposals face political resistance, concerns over state sovereignty, and limited consensus on burdensharing, which hinder progress.60 In practice, most protections remain nonbinding, fragmented, and reactive, leaving climate migrants vulnerable to inconsistent treatment, xenophobia, and exclusion from resettlement programs. These gaps underscore the need for a coherent, enforceable global standard that integrates migration policy with climate adaptation and human rights protections. HEALTH EQUITY IN EMERGENCY DISASTER RESPONSE: GAPS AND OPPORTUNITIES Health equity in disaster response means that all people

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Table 2. Current legal and policy protections for people displaced by climate change. Legal or Policy Approach

Mechanism of protection

Regulatory body

Strengths

Gaps

1951 Refugee Convention and 1967 Protocol

Defines “refugee” based on persecution; the principle of nonrefoulement.

UNHCR / States Parties

Binding, widely ratified international status and protections.

UN Guiding Principles on Internal Displacement (1998)

Soft-law human-rights standards for IDPs, including those displaced by disasters.

UN (OCHA), implemented by states

Explicitly applicable to Nonbinding, no disaster-related IDP; widely enforcement, applies only used normative guide. within a person’s own country.

Kampala Convention (2009)

Regional treaty protecting IDPs due to conflict and natural disasters.

African Union / States Parties

A binding regional law that explicitly covers disaster and climate-related displacement.

Paris Agreement - Article 8 & WIM (2015)

Political framework to address loss or damage and displacement, WIM coordinates workstreams and support.

UNFCCC / Formally recognizes Conference of the displacement associated Parties with climate impacts and provides an institutional home for coordination and finance discussions.

Global Compact for Safe, Orderly and Regular Migration (2018)

Non-binding cooperation UN system (IOM/ framework acknowledging UN Migration climate and environmental Network) drivers of migration.

Recognizes climate as a migration driver, encourages policy coordination and data.

Voluntary creates no legal status or justiciable rights.

Teitiota v. New Zealand (UN, HRC, 2020)

HRC found climate impacts can, in some cases, trigger nonrefoulement under ICCPR (right to life).

UN HRC

First UN treaty body view recognizing climate risk may bar removal where life risk is substantial.

Views do not capture other “climate refugee” statuses, are case-bycase, and are non-binding on all states.

G20 LEMM Fortaleza Declaration (2024)

Re-affirms just transition, commits to addressing labor inequities, occupational safety (heat stress), and social protection in the context of climate change.

G20 and Employment Ministers

Global political momentum Non-binding declaration, is linked to climate change, relies on national uptake work, a just transition, and G20 follow-through. and worker protections. Endorses the ILO Decent Work Agenda.

The definition does not cover displacement solely from climate or environmental causes.

Regional (Africa-only)

Lacks enforceable individual rights, finance, and operationalization remain limited.

HRC, Human Rights Council; ICCPR, Initialism of International Covenant on Civil and Political Rights; IDP, internally displaced persons; ILO, International Labour Organization; IOM, International Organization for Migration; LEMM, Labour and Employment Ministers’ Meeting; OCHA, Office for the Coordination of Humanitarian Affairs; UN, United Nations; UNFCCC, United Nations Framework Convention on Climate Change; UNHCR, United Nations High Commission for Refugees; WIM, Warsaw International Mechanism.

have equal access to timely warnings, emergency care, and recovery resources regardless of language, income, or legal status. Emergency departments (EDs) often serve as a first point of care during crises and are designed to provide acute stabilization. However, sometimes, EDs are also the only point of care for those impacted by climate disasters. When ED care is not followed by longitudinal care or postdisaster follow-up by pre-existing or temporarily activated systems, critical gaps in ongoing health management can arise for affected populations.61 International health care systems are increasingly strained by climate-related events such as heat waves, floods, and storms, and many are still working to develop the necessary infrastructure, staffing, and preparedness systems to effectively Western Journal of Emergency Medicine

incorporate climate resilience into their daily operations.62 While there are increasing efforts to incorporate focused consideration of vulnerable populations in disaster response planning, refugee and immigrant populations have been historically excluded and face additional barriers to participation, such as fear of immigration and enforcement and lack of trust in health systems.63–65 Without sustained investment for interpreter services, culturally informed care models, and long-term recovery mechanisms, EDs and disaster systems will continue to fall short of providing equitable care during and after climate-related events. Disaster response systems face interconnected barriers that operate across communication, policy, and workflow

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Mundo et al. levels. These challenges increase risk for linguistic minorities, undocumented immigrants, and low-income communities, contributing to preventable illness, delayed recovery, and systemic exclusion (Table 3). Emergency communications are often issued only in the dominant language, leaving many unable to receive timely evacuation orders, health advisories, or hazard updates.66,67 In Australia, mortality rates among people born overseas during disasters were nearly three times higher than for those born locally, mainly due to language barriers and limited English or digital literacy.68 Similar issues occur in multilingual regions of the U.S., where residents with limited English proficiency report missing critical alerts or misunderstanding evacuation instructions when messages are not translated or delivered through digital platforms inaccessible to older, rural, or low-income populations.66,69 Adding to these barriers is a reliance on superficial cultural competency. Training is often viewed as a mere compliance requirement rather than an integral part of implementation that genuinely incorporates multilingual, culturally-tailored communication strategies into disaster response.70–72 Emergency operations plans and emergency preparedness guides rarely incorporate immigration status, language access, or health literacy into planning, defaulting to a “one-size-fitsall” approach that incompletely accounts for inequities influencing exposure, evacuation, and recovery.73 Recovery services, including housing assistance, medical care, and financial aid, are more difficult for non-English speakers to access due to a lack of multilingual navigation support, exacerbating disparities long after the disaster impact.11,74 Even when cultural competency is included in preparedness frameworks, it remains challenging to operationalize, given

the many layers of disaster response.75 The result is a persistent inequity, where populations with limited access before a disaster often experience delayed recovery afterward, reinforcing structural vulnerability rather than resilience. Addressing these inequities requires reframing disaster response as an equity-centered system rather than simply a logistical operation. Disasters reveal, rather than create, the structural weakness of health and social systems. Embedding equity into disaster planning demands more than translation services or temporary outreach. It requires the consideration of the factors underlying who are most affected and why they are vulnerable. This shift helps lay the foundation for innovation that applies implementation science to sustain equitable outcomes across all phases of the disaster cycle. INNOVATIONS AND SOLUTIONS: CENTERING EQUITY IN DISASTER RESPONSE A structured framework is essential to translate equity from principle to practice in disaster response. The Practical, Robust Implementation and Sustainability Model (PRISM) and the Reach, Effectiveness, Adoption, Implementation, Maintenance (RE-AIM) framework together offer a pragmatic, evidencebased approach for designing, evaluating, and sustaining interventions in the real world.76,77 While PRISM identifies how contextual, organizational, and recipient-level factors shape the feasibility and sustainability of disaster interventions, RE-AIM provides measurable domains for assessing reach, adoption, and long-term impact. Applying these models to disaster planning allows policymakers and practitioners to identify equity gaps early, tailor interventions to local needs, and monitor implementation of integrated strategies across policy reform,

Table 3. Multi-level barriers to equitable disaster response and their proximal and distal impacts. Barrier

Proximal Impact

Distal Impact

Language access gaps

Missed warnings, miscommunication during medical care, and difficulty locating shelters or evacuation routes.

Reinforcement of systemic inequities in disaster communication, erosion of trust in institutions, and widening health disparities among language minority communities.

Fear of immigration Avoidance of shelters and medical care, enforcement or delayed or forgone treatment during documentation concerns emergencies.

Entrenchment of exclusionary systems that discourage immigrant populations from engaging with disaster infrastructure.

Poverty and resource limitations

Inability to purchase supplies, evacuate, or rebuild, and greater exposure to unsafe conditions.

Cyclical dependency on overstretched aid systems, slower community recovery, and intergenerational loss of wealth and stability.

Preparedness and workforce capacity

Lack of trained interpreters, multilingual Systemic underinvestment in equitable preparedness responders, and culturally responsive clinicians infrastructure and limited institutional capacity to adapt to during crises. diverse populations in repeated disasters.

Data collection Lack of recognition of disparities at the Persistent gaps in preparedness planning and policychallenges and individual level, and invisibility of vulnerable making, structural neglect in resource allocation, and situational awareness populations in immediate disaster statistics. recovery funding. gaps COPD, chronic obstructive pulmonary disease; PTSD, post-traumatic stress disorder.

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Advancing Equity in Climate-Driven Disaster Response community-based response, and technology innovation to advance equitable disaster systems (Figure). The domains of PRISM could offer a structured approach to align context-specific needs with sustainable interventions, reducing the fragmentation that often undermines disaster response at all stages (Table 4). By mapping environmental, organizational, and recipient factors to each disaster phase, PRISM helps planners anticipate barriers such as funding gaps, workforce shortages, or cultural misalignment before they derail implementation. Integrating this framework with RE-AIM ensures that interventions are both deployable under crisis conditions and evaluated for long-term impact. Policy reforms rooted in PRISM principles can embed equity audits into zoning and funding decisions; community innovations can train and deploy culturally responsive responders; and technology solutions can standardize multilingual communication systems. Together, these approaches demonstrate how implementation science transforms disaster management from reactive aid delivery to a sustained, equitydriven system of preparedness, response, and recovery. Policy and System-Level Interventions Applying PRISM and RE-AIM to disaster policy offers a structured way to operationalize equity across systems that have historically prioritized speed over inclusion while recognizing how sustainability and health equity are critical metrics for program success.78,79 These frameworks encourage

Figure. Conceptual Practical, Robust Implementation and Sustainability Model/Reach, Effectiveness, Adoption, Implementation, Maintenance framework illustrating integrated policy, community, and technology strategies to advance equity in climate-related disaster preparedness and response. The model links contextual factors, organizational and community perspectives, targeted implementation strategies, and equityfocused outcomes to guide design, scaling, and sustainability across austere settings.

Western Journal of Emergency Medicine

Mundo et al. policymakers to analyze how environmental context, organizational readiness, and community engagement influence program sustainability and reach. Embedding this perspective into climate-informed disaster planning enables agencies to map priority populations into preparedness protocols and funding mechanisms. Integrating PRISM and RE-AIM principles can also align policy interventions with existing infrastructure and trusted local networks, supporting equitable scale-up while maintaining feasibility.77 Practical applications include expanding emergency health financing and codifying language access requirements into emergency operations plans and drills. Institutional accountability through performance metrics that are tied to equity outcomes ensures these reforms move beyond symbolic commitments toward measurable, system-level change. Community-Based Innovations The PRISM framework has demonstrated value in community health worker and clinical settings where interventions were adapted to local realities while maintaining measurable outcomes.80 One illustrative example comes from Haiti’s 2010 cholera outbreak, where a national health agentled surveillance and education program effectively reduced mortality through community trust and locally embedded training.81 Although disease-specific, the model’s success demonstrates how community-trusted intermediaries can strengthen disaster systems in low-resource settings. Applied to climate-related disasters, this approach involves deploying community health workers trained to identify climate-sensitive hazards, coordinate early response, and deliver culturally and linguistically aligned outreach.82 The focus of PRISM on the external environment and recipient engagement provides a framework for tailoring community health worker deployment to community networks, such as churches, shelters, and neighborhoods. Just-in-time responder training, focused on cultural humility, operational stress injury, and bias, could help responders rapidly adapt to the social and cultural context while mitigating and preventing trauma caused by discrimination or miscommunication.83–85 Crisis navigation hubs that integrate legal aid, health care, and housing services in one-stop centers could address the fragmentation that often undermines recovery for displaced individuals.86 These multi-sector models exemplify how implementation frameworks bridge the gap between policy vision and lived community experience. Communication and Technology An implementation science approach can identify contextual barriers such as language, digital access, and trust, which often determine whether communication strategies succeed or fail. By applying these principles, planners can ensure that technology-based interventions are adapted to community capacity and cultural context rather than imposed from the outside. Practical strategies include mobile, 150

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Table 4. Practical, Robust Implementation and Sustainability Model-aligned disaster phase-specific innovations examples. Disaster Phase

External Environment

Recipients

Design and Adaptation

Infrastructure

Mitigation and Prevention

Long-term policy reforms, land-use planning, and investment in climate projects such as resilient housing and infrastructure.

Linguistic minorities and undocumented communities in highrisk zones.

Inclusion of equity audits in zoning and housing codes, and expansion of flood insurance access, integrated exercises with linguistic minority individuals

Sustainable funding for resilient infrastructure, integration of climate migration into urban planning.

Preparedness

Community risk mapping

CHW outreach to linguistic minority and/ or undocumented residents

Multilingual early warning systems

Language-trained hotline staff, mobile alert platforms

Response

Coordination with local and state government agencies, NGOs, and the community

Displaced and medically complex patients

Mobile clinics, pop-up pharmacies

Cross-trained interpreters in care areas, telehealthenabled triage

Recovery

Policy reform for ID-free aid access

Linguistic minority Simplified aid applications, peer or and low-literacy cultural navigator programs populations CHW, community health worker; ID, identification; NGO, non-governmental agencies.

multilingual response units that deliver real-time updates and triage support after disasters, and hyper-localized, multilingual warning systems using short message service (SMS), radio, and trusted community messengers. Artificial intelligenceenabled translation and natural language processing tools can enhance accessibility in clinical workflows by generating personalized, easy-to-read discharge summaries in multiple languages or community alerts, thereby embedding language accessibility into digital health solutions.87 These solutions must be deployed within transparent governance models for digital health research that aim to enhance data quality and translate research findings into integrated frameworks for planning, executing, and assessing public health initiatives.88 Integrating technology with policy reform and community innovation within the PRISM and RE-AIM frameworks provides a unified model for equitable disaster preparedness and response. This model explicitly maps vulnerable populations within preparedness plans, aligns interventions with trusted local infrastructure, and embeds language accessibility into both policy and practice. Deploying multilingual response units, community health workers, and culturally adapted training creates a multi-level approach that connects communication, clinical care, and recovery support. When equity becomes a design requirement rather than a retrospective correction, disaster systems move closer to achieving resilience that includes every community. CONCLUSION Displacement, disconnection from care, and systemic neglect fall heaviest on those individuals without legal protections, linguistic minorities, and economically marginalized communities. Existing disaster management Volume 27, Supplement: November 2026

Sustained funding for CHW networks, legal aid partnerships

frameworks, designed for speed rather than equity, can leave these populations disproportionately vulnerable to disaster impacts. By aligning community-based solutions, policy reforms, and technology innovations within implementation science frameworks, disaster response can be transformed to incorporate a proactive approach to improve equity. The climate crisis is inseparable from the equity crisis; only by addressing both together can disaster response systems be built to truly safeguard every community when the waters rise.

Address for Correspondence: William Mundo, MD, MPH, University of Colorado Anschutz School of Medicine, Department of Emergency Medicine, 12401 East 17th Ave, 7th Floor, Aurora, CO 80045. Email: william.mundo@cuanschutz.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Mundo et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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Volume 27, Supplement: November 2026

Climate Change: Original Research

Sustainability in Quality Improvement: Outcomes of a Novel Pediatric Virtual Urgent Care in Ontario, Canada Emma Lim, BsC* Julie Strychowsky, MD†‡|| Anna C Gunz, MD§|| Sheena Belisle, MD§

*McMaster University, Michael G DeGroote School of Medicine, Hamilton,

Ontario, Canada Western University, Schulich School of Medicine and Dentistry, Department of Surgery, London, Ontario, Canada; ‡ London Health Sciences Centre, Department of Otolaryngology - Head and Neck Surgery, London, Ontario, Canada; § Western University, Schulich School of Medicine and Dentistry, Department of Paediatrics, London, Ontario, Canada; || Child Health Research Institute, London, Ontario, Canada †

Section Editor: Robert Flint, MD, FACEP, FAAEM Submission history: Submitted November 24, 2025; Revision received April 4, 2026; Accepted March 30, 2026 Electronically published July 28, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.54076

Introduction: Virtual care is expected to play an increasingly important role in the Canadian healthcare system, with the 2023-2024 Health Canada Departmental Plan outlining the advancement of digital health solutions as a focal point. However, key outcomes of transitioning from traditional in-person healthcare appointments to a virtual model of care are not yet welldescribed. Here, we apply the Sustainability in Quality Improvement (SusQI) framework to patients seen in a novel pediatric virtual urgent care (VUC) program to quantify the environmental, economic, and social impacts of virtual care. Methods: We conducted a retrospective analysis of provincial pediatric VUC visits staffed by pediatric emergency physicians and nurse practitioners during the 2020-2025 fiscal years. We focused on three key metrics: (1) economic value, measured as travel costs avoided; (2) environmental value, measured in fuel saved (L) and carbon emissions reduced (kg CO₂ eq); and (3) social value, assessed using Ontario Marginalization (ON-Marg) Index quintiles. Results: A total of 12,900 virtual visits were completed during the study period, 99.9% via the Webex platform. Net savings totaled $998,100. Environmental benefits included 128,700 L of fuel saved and 384,200 kg CO₂ eq emissions avoided. Summary ON-Marg Index scores were similar between groups (2.87 for in-person emergency department (ED) visits; 2.91 for virtual visits). Data collected between July 2023-April 2025 show that 10.6% (353) of visits resulted in subsequent inperson ED presentation. Conclusion: Virtual urgent care resulted in significant financial and environmental savings per visit. These benefits included reduced financial and time burdens for families, lower hospitalrelated expenditures, improved environmental performance, and diversion of low-acuity cases from the ED. Comparable ON-Marg scores between patients seen virtually and in-person suggest accessibility across socioeconomic groups. These findings indicate that pediatric VUC is a viable complement to traditional care, providing meaningful cost and environmental savings while ensuring equitable access. [West J Emerg Med. 2026;27(6.1)155–162.]

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Outcomes of a Novel Pediatric Virtual Urgent Care in Ontario, Canada INTRODUCTION Climate change is an area of significant concern within healthcare. The effects of climate change pose an imminent threat to human health, increasing morbidity and mortality, widening existing social disparities, and increasing the burden on healthcare services.¹ The development of sustainable healthcare systems can be achieved through mitigation policies aimed at reducing carbon emissions and by identifying ways to create more robust healthcare infrastructure.² Virtual care is one promising avenue for carbon reduction, as it eliminates the need for patients to travel to clinics, reducing their reliance on fossil fuels.3,4 Virtual care may also improve access by reducing the time, distance, and effort required by patients attending appointments.5,6 Understanding the profile of carbon emissions associated with virtual and in-person care can guide the development of a more sustainable healthcare system.⁷ In 2020, as part of the COVID-19 pandemic response, the Ontario Ministry of Health approved $4 million in funding for regionally coordinated virtual urgent care (VUC) initiatives across Ontario.⁸ A 2023 cross-sectional survey evaluating patients using VUC services in Ontario found that 94% of patients rated their experience as 8/10 or greater, with more than 80% saying they felt confident managing their presenting concern.⁹ Virtual care continues to be used across multiple medical specialties. In 2021, during the pandemic, approximately 40% of all healthcare visits in Canada were virtual.10 The 2023-2024 Health Canada Departmental Plan outlined the advancement of digital health solutions as a focal point, indicating the increasingly important role virtual care is expected to play in the Canadian healthcare system.11 The primary goal of this paper was to examine the value of VUC in patients who would otherwise present to a pediatric emergency department (ED) by quantifying associated savings. A secondary goal was to explore the various impacts of its continued use as a substitute for in-person emergency medicine in applicable patients. We also aimed to evaluate disparities in access to care by comparing the demographic makeup of patients accessing virtual versus in-person emergency services. This assessment focused on three key areas: financial; environmental; and social considerations. This analysis was guided by the Sustainability in Quality Improvement (SusQI) framework, developed by the Centre for Sustainable Healthcare (CSH) in the United Kingdom.¹² The SusQI framework focuses on the CSH principles of sustainable clinical practice and measures the health outcomes of a service against the Triple Bottom Line model introduced in 1997 by economist John Elkington. This model examines sustainable development through a multifaceted lens of social, environmental, and economic sustainability.¹³ Here, we used the SusQI framework to provide an understanding of the value of virtual care and the potential for expansion and application within other healthcare domains.

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Lim et al. Population Health Research Capsule What do we already know about this issue? Virtual care is expected to play an increasing role in healthcare, but its broader environmental, economic, and social impacts remain poorly characterized. What was the research question? To quantify the financial, environmental, and social impacts of pediatric virtual urgent care using the Sustainability in Quality Improvement framework. What was the major finding of the study? Virtual urgent care saved $998,100, 128,700 L of fuel and 384,200 kg CO₂ across 12,900 visits with 10.6% directed to the emergency department. How does this improve population health? Virtual urgent care reduces emissions and financial burden while improving access to care, which supports the development of more sustainable and resilient healthcare systems.

METHODS Study Design We conducted a retrospective analysis of patients presenting to the pediatric Ontario VUC program operating out of the hospital. This was part of a joint pilot initiative to offer virtual services to residents in southwestern Ontario. The service was publicly available and promoted through institutional communications and news articles. Individuals accessed the VUC through the Urgent Care Ontario website. Virtual visits were conducted using the Webex application, a secure videoconferencing platform. Pediatric patients were defined as individuals ≤ 17 years of age at the time of their visit. No exclusion criteria were applied. Data were sourced from the hospital virtual care dashboard, developed by the hospital decision support team. The dashboard collects data on all patients who received outpatient care at the hospital since 2020. All patients who used pediatric VUC during the fiscal years of April 2020-March 2025 were captured in our analysis. Clinical variables were extracted automatically; therefore, no manual chart review was deemed necessary. Available variables include the volume of in-person and virtual visits, financial and travel savings associated with virtual visits, and Ontario Marginalization (ON-Marg) Index scores. We also collected ON-Marg scores for in-person ED visits occurring

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during the same time periods. Data on subsequent presentation to ED was captured by standardized fields within the clinical virtual care note indicating clinician recommendation to seek further care at an ED. In addition, we invited all patients who used pediatric VUC to complete a feedback survey one month after their visit which included questions regarding serious adverse events.

quintile scores for the above domains between patients who attended in-person and those who opted for virtual care to evaluate disparity in access to virtual care. Comparisons were based on postal code data and conducted across the four-fiscalyear study period. Additionally, we examined ON-Marg scores annually to address changes in the sociodemographic characteristics from year-to-year.

Calculation of Savings Postal codes were used to calculate travel distances, which were approximated based on the straight-line distance between the home address and the location of the children’s hospital. Monetary savings were calculated using the 2022 mileage reimbursement rate of $0.69 CAD per km set by the Canadian Revenue Agency.14 Fuel savings were estimated using the average fuel consumption rate of 8.9 L per 100 km from the Canada Energy Regulator.15 A conversion factor of 0.2656 kg CO₂-equivalent per km sourced from Canada Health Infoway was used to quantify carbon emissions avoided.16

Data Analysis We summarized study outcomes with descriptive statistics including frequency statistics, means, and standard deviations. Unpaired t tests were conducted to compare outcomes between in-person and VUC visits. Mann-Whitney U tests were conducted to compare ON-Marg quintile values as quintile values are ordinal. One-way analysis of variance (ANOVA) with a post hoc Bonferroni test was used to assess differences between savings across fiscal years. Statistical significance was set at ⍺ = .05.

Calculation of Ontario Marginalization Index Scores We calculated ON-Marg quintile scores according to the methodology outlined by Paczkowski et al (2024).17 We used the ON-Marg index to evaluate disparities in access to virtual care within the study population. Developed by Public Health Ontario from the Canadian Marginalization Index, the index groups area-level census indicators into four dimensions: households and dwellings; material resources; age and labor force; and racialized and newcomer populations.18 Households and dwellings include indicators that measure the following: the type and density of a residential accommodation, such as the percentage of rental dwellings and apartments; price of property; and structural characteristics of the family, such as the percentage of residents living alone, the percentage of residents who moved within five years, the number of residents per dwelling, and percentage of residents who are widowed or divorced. Material resources include indicators that measure the access and attainment of material needs such as income, the percentage of employed individuals, and the percentage of individuals with a high school degree. Age and labour force includes the dependency ratio (children < 15 and adults > 65 relative to the general population), proportion of seniors and children, and labor force participation. Racialized and newcomer populations includes the percentage of recent immigrants and the percentage of individuals who selfidentify as belonging to a minority group. We assigned each Ontario neighborhood a quintile score from 1 (least marginalized) to 5 (most marginalized) for each domain. Higher values indicate greater levels of marginalization, where each quintile represents one-fifth of the geographic units. A score of 5 therefore represents the most deprived 20% of regions in Ontario. We compared ON-Marg Volume 27, Supplement: November 2026

RESULTS A total of 12,900 VUC visits were completed during the study period, 99.9% of which were conducted via the Webex platform. Although data was not available for the entire study period, data collected between July 2023-April 2025 indicate 10.6% (353) of VUC visits resulted in a recommendation to seek care in-person at an ED. No serious adverse events were reported through the standardized postvisit feedback surveys during this period. Economic Outcomes Across all five fiscal years (2020-2025), the pediatric VUC program generated an estimated $998,100 in cost savings (Table 1). Although the total savings varied in proportion to the number of visits per year, average per-visit savings increased steadily, peaking at $118.30 in 2024-2025 (Table 2). Environmental Outcomes The program was associated with cumulative savings of 128,700 L of fuel and a reduction in emissions of 384,200 kg CO2 eq (Table 1). Per-visit savings increased

Table 1. Total savings associated with virtual urgent care during the fiscal years of 2020-2025. Total Savings Number of Visits

12,900

Cost Savings ($)

$998,100.00

CO2 (t)

384.20

Fuel (L)

128,700

CO2, carbon dioxide; L, litre; t, tonne.

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Table 2. Annual Savings with average per visit savings. For each outcome, the total value for each fiscal year is presented, with the average saving per visit shown in parentheses. Per-visit values were calculated by dividing the yearly savings by the number of visits in that fiscal year. Outcomes include total cost savings (in $CAD), total carbon emissions avoided (kg CO₂ equivalent), and total fuel savings (litres). Fiscal Year Number of visits

2020-2021

2021-2022

2022-2023

2023-2024

2024-2025

1421

4195

3703

1624

1957

Total cost savings ($)

$50,400 ($36.60)

$237,600.00 ($59.50)

$298,700 ($83.40)

$183,800 ($115.40)

$227,600 ($118.30)

Total CO2 (kg CO2 eq)

19,400 (14.11)

91,400 (22.91)

115,000 (32.1)

70,800 (44.42)

87,600 (45.52)

6,500 (4.7)

30,600 (7.7)

38,500 (10.8)

23,700 (14.9)

29,400 (15.3)

Total fuel savings (L)

kg CO2 eq, kilograms of carbon dioxide equivalent; L, litre.

annually, reaching 15.3 L of fuel and 45.52 kg of CO₂ per visit in 2024-2025 (Table 2). Figure 1 illustrates both the annual total savings and the annual per-visit savings. While total savings generally reflected program volume, the increase in per-visit savings over time suggests that the average travel distance avoided per virtual visit increased during the study period.

environmental benefit, as it does not account for decreased CO2 emissions from travel avoided by clinicians, or the consumption of electricity and medical resources associated with in-person care. There were also clear economic benefits, with an estimated $998,100.00 in travel costs saved over the five fiscal years. Our findings are consistent with the literature. A previous cost analysis of VUC in an American setting found an associated savings of $93.657 USD ($132.80 CAD) per visit.21 Similarly, a study of 63 million

Social Outcomes There were no significant differences in ON-Marg index quintile scores between patients presenting to VUC versus in-person ED visits for household and dwelling, age and labor force, or racialized and newcomer populations domains (Table 3). Summary ON-Marg scores were similar overall (2.91 for VUC vs. 2.87 for in-person visits) (Table 4). Travel Distance Figure 2 depicts visit density by patient travel distance. The mean travel distance was 40.6 km, with greater per-visit fuel and CO₂ savings observed year-over-year. DISCUSSION To our knowledge, this is the first study to evaluate a pediatric VUC program using the SusQI framework. Our findings show that VUC is a cost-effective, environmentally sustainable, and accessible model of care. We found that the vast majority of cases did not result in in-person presentation, suggesting VUC can reduce the burden on healthcare systems by addressing low-acuity patient concerns. Over the five-year study period, VUC was associated with an estimated reduction of 384,200 kg CO₂ eq and an estimated $998,100 CAD in avoided patient travel costs. For context, the total 384,200 kg CO₂ eq is equivalent to the annual electricity consumption of about 80 households or 426,775 lbs of coal burned, according to the Greenhouse Gas Equivalencies calculator.19 The VUC program’s reductions represented 0.73% of total hospital emissions as given by our hospital’s 2021 annual emissions of 54,439 tonnes CO₂.20 It is worth noting that this number may significantly underrepresent the actual Western Journal of Emergency Medicine

Figure 1. Financial and environmental savings of virtual care. Graphs A–C show annual total cost, CO₂ eq, and fuel savings, while graphs D–F show corresponding annual per-visit savings. Total savings were driven by both the number of virtual visits and the average travel distance avoided. CO2, carbon dioxide.

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Table 3. Annual Ontario Marginalization Index Scores of patients seen virtually. Fiscal Year 2020-2021

Fiscal Year 2021-2022

Fiscal Year 2022-2023

Fiscal Year 2023-2024

Fiscal Year 2024-2025

Household and dwellings

2.98

2.99

3.09

3.13

3.08

Material resources

2.81

2.83

2.92

2.9

2.94

Age and labor force

2.46

2.59

2.75

2.95

2.94

Racialized and newcomer populations

3.14

3.08

3.04

2.87

2.75

Summary score

2.85

2.87

2.95

2.96

2.93

Outcome

virtual care visits in Ontario found that virtual care averted approximately 3.2 billion km of patient travel, or 545-658 million kg of CO2 eq.22 We found that VUC usage peaked between the 2021-2022 and 2022-2023 fiscal years, likely reflecting the COVID-19 pandemic. Virtual health and telehealth visits increased significantly during the COVID-19 pandemic, likely reflecting both public health measures and widespread attitudes towards in-person care during the pandemic.25 Although the total number of visits in 2024-2025 was below peak usage, usage increased from 2023-2024 to 2024-2025, reflecting sustained interest over time. Interestingly, total cost savings grew more rapidly than the number of patient encounters. We found that the savings per-visit increased annually, even when overall VUC usage declined from peak levels. This reflects a shift in the demographics of VUC users towards individuals living further away. It may also indirectly reflect the increasing economic burden of commuting which includes rising fuel and operating expenses. Deferred Emergency Department Visits Only 10.6% (353) of VUC visits during July 2023-April 2025 resulted in an in-person ED visit. This number is lower than the 17.2% of visits resulting in ED referral found by a 2020-2021 prospective study analyzing data from VUC services at 14 ED-led pilot sites in Ontario, Canada.9 The higher rate of in-person presentation during that period may reflect the unique social environment of the pandemic which was not captured in our analysis of in-person visits. We hypothesize more patients presented to VUC with concerning symptoms because they were afraid to access in-person care. It is important to note that VUC services are inherently different than the services provided at an in-person ED. Virtual urgent care clinicians are not able to provide a physical examination or access real-time laboratory testing or imaging. In addition, VUC clinicians are often unable to access previous medical records, all of which limit their ability to provide an accurate diagnosis.23 Similarly, the population of patients who use VUC services may also be intrinsically different than the population presenting to Volume 27, Supplement: November 2026

in-person EDs. Research has shown that the majority of VUC visits were by patients with low-acuity concerns who have access to primary care.24 Equity and Access A 2023 study by Williams et al found that telehealth was associated with widening health inequalities, with lower household income and ethnic minority associated with lower use of video health services, attributable to the cost of technology and the costs associated with missing work.25 Contrary to these findings, we observed no discrepancy in access to care across sociodemographic domains, as measured by the ON‐Marg index, indicating that VUC remained accessible to patients with lower household income or those living in rural or underserved locations. Our results also indicated non-English speakers were equally likely to use both deliveries to access care. Our findings also did not substantiate the findings of Hall et al who found that patients who use the ED for low-acuity problems were unable to use VUC because they did not have access to a computer or smartphone.23 Although we did not find a significant difference in marginalization status between patients using virtual and in-person care, we recognize that technological barriers remain a substantial challenge. Individuals accessing VUC must have WIFI and access to a device with video and microphone capability. They must also be able to install the Webex mobile application and have an email address to access the appointment link. It is possible that the small subset of patients who are most affected by technological barriers were not fully captured in our analysis, highlighting the need for more research specifically focused on accessibility. Transportation barriers have also been shown to significantly restrict healthcare access, particularly for patients with lower incomes.26 Longer travel times correlate with a greater number of missed appointments and lower treatment adherence.27 Our analysis of travel distances complements these findings. During the 2023-2024 fiscal year, the mean travel distance was 40.61 km from the children’s hospital, suggesting VUC may decrease the burden of longer travel times. Virtual urgent care may also be more accessible because it eliminates

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Table 4. Average Ontario Marginalization Index Scores of patients seen virtually versus in person across all years. Outcome

In-Person Mean (SD)

Virtual Mean (SD)

Household and dwellings

3.10 (0.38)

3.05 (0.07)

(P = .70)

Material resources

2.73 (0.52)

2.88 (0.06)

(P = .57)

Age and labor force

2.45 (1.00)

2.73 (0.22)

(P = .90)

Racialized and newcomer populations

3.22 (0.51)

2.97 (1.15)

(P = .49)

2.87

2.91

Summary score SD, standard deviation.

barriers such as transportation costs and childcare, which can make attending in-person appointments prohibitive. In addition, VUC may also provide access to specialists and services not available in rural or underserved locations. Strengths This study addresses an important gap in the literature by providing one of the first multi-year evaluations of pediatric VUC. To our knowledge, this is the first study that focuses on the economic and environmental impacts of VUC in pediatric emergency care. Clinical Implications The findings suggest that pediatric VUC is a viable strategy to reduce unnecessary ED visits while alleviating some of the financial and logistical burdens placed on families. Cost savings extend beyond direct travel expenses to include indirect benefits such as reduced need for childcare, less time off work, and greater flexibility for families. Importantly, VUC appears to be accessible to marginalized populations, particularly those in rural areas. The use of virtual care may also provide additional benefits to both clinicians and patients, such as a reduction in unnecessary appointments, leading to decreased wait times and increased efficiency. Similarly, VUC may also increase flexibility and work-life balance. Research has shown that emergency physicians

Figure 2. Travel distance (km) and number of visits in the 20232024 fiscal year. km, kilometre.

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appreciated the opportunity to interact with patients outside the chaotic environment of the ED.23 Finally, the broader environmental benefits extend beyond quantifiable environmental savings. Virtual care signifies a transition toward more sustainable and more robust healthcare systems. The U.S. Agency for International Development (USAID) Health System Strengthening Vision 2030 outlines the need for resilient healthcare systems to adapt to “acute, time-bound events; and longer-term destabilizing dynamics.”28 In many regions in Canada, healthcare services have become increasingly centralized in larger urban centers, leaving smaller communities with limited local options. The reliance on urban facilities creates significant challenges for patients, even under normal conditions. Climate-related disruptions may therefore severely compromise access to care. We found that the greatest proportion of emission reduction occurred in patients living in rural areas. The reduction in travel associated with urgent care can improve overall access to care while also bolstering the continuity of care during climate-related disruptions. Virtual urgent care may also alleviate pressure on the healthcare system by diverting less urgent cases, allowing EDs to better adapt to increased demand. Our findings support the implementation of VUC as an important step towards more resilient healthcare systems. Research Implications Future research should further explore the long-term cost-effectiveness of VUC. More robust environmental evaluations are also warranted, particularly research which examines the consumption of hospital resources associated with in-person care. From a social perspective, further investigation is needed into barriers such as digital literacy, technology access, and language support, as these remain potential obstacles to equitable use. In addition, the ED presents a confusing and often frightening experience for children, and it would be interesting to explore how pediatric patient experience differs between VUC and ED, as well as the attitudes and experiences of their families. LIMITATIONS This study has several limitations. Although we captured

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clinician recommendations for in-person care and monitored adverse events through patient feedback surveys, we did not perform a formal chart review to verify clinical outcomes. As this study was designed to estimate financial and environmental savings using administrative dashboard data, it was not powered or structured to formally assess safety. Therefore, we are unable to draw definitive conclusions regarding diagnostic accuracy, missed diagnoses, or the overall safety profile of the VUC model. Furthermore, the retrospective nature of this study meant that only data collected by the hospital virtual care dashboard could be included. While our research has shown a substantial cost savings per visit, it may not capture the full range of expenses typically associated with travelling to in-person ED visits, such as parking, travel costs, lost wages, and other indirect expenses such as food or accommodations. We also were not able to quantify patient-specific choices, such as patients who may have chosen to take alternative methods of transportation (eg, public transport or walking) or patients who might have chosen to present to their family doctors or closer nonpediatric EDs instead of our institution. In addition, an in-person visit to a pediatric ED often incurs additional costs compared to a visit to a general ED, as parents or caregivers may need to arrange childcare for other children. The need to take time off work may compound the financial and logistical burden for families presenting to pediatric urgent care, leading to the potential for additional loss of income not associated with adult urgent care. As these variables were not included in the hospital virtual care dashboard, they unfortunately could not be included in our analysis. As our methodology used straight line distances to approximate travel distances, it is very likely it underrepresents travel time needed by car. Similarly, we estimated monetary and fuel savings using set rates. While these provide good approximations, they do not fully capture the volatility of gas prices across multiple years. Given this, and our inability to calculate indirect expenses, it is therefore likely that our results underestimate the full cost savings of VUC. CONCLUSION At a time when we are facing a climate crisis, with healthcare systems seeking to reduce their environmental footprint, our findings demonstrate that pediatric VUC is a sustainable model of care. In our multi-year evaluation, VUC generated significant reductions in fuel consumption, travel time, and CO₂ emissions, while also alleviating the burden on the ED. Importantly, VUC remained accessible across marginalized and rural populations. The real-world applications of our findings are significant and support the broader adoption of virtual care across the healthcare sector. Virtual urgent care should be considered a key component of future care models as healthcare systems build sustainability and resilience. Volume 27, Supplement: November 2026

Address for Correspondence: Emma Lim, BsC, McMaster University, Michael G DeGroote School of Medicine, 1280 Main St W, Hamilton, ON L8S 1C7. Email: emma.lim@medportal.ca. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Lim et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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20. Regulatory compliance | LHSC. Available at: https://www.lhsc.on.ca/

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21. Khairat S, Lin X, Liu S, et al. Evaluation of patient experience during

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14. Agency CR. Automobile or motor vehicle benefits – allowances or

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December 23, 2024.

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rank in terms of vehicle fuel economy?. 2023. Available at: https:// www.cer-rec.gc.ca/en/data-analysis/energy-markets/market-

Canada. Front Digit Health. 2022;4:946734. 24. McLeod SL, Tarride JE, Mondoux S, et al. Health care utilization and

snapshots/2019/market-snapshot-how-does-canada-rank-in-terms-

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vehicle-fuel-economy.html. Accessed December 23, 2024.

emergency department care. CMAJ. 2023;195(43):E1463-E1474.

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17. Paczkowski F, Gandhi K, Dzioba A, et al. Economic, environmental, and social value of virtual care in otolaryngology: sustainability in

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Volume 27, Supplement: November 2026

Climate Change: Original Research

Impact of Increasing Ambient Temperatures on Emergency Department Trauma Presentations at a Level I Trauma Center Grace E. Mosley, MD, PhD*†o Monique Arnold, MD*†o Bharti Sharma, MS‡ Jennifer Whittington, MD, PhD§ Geoff Jara-Almonte, MD†

*Icahn School of Medicine at The Mount Sinai Hospital, Department of Emergency Medicine, New York, New York † NYC Health and Hospitals, Elmhurst Hospital Center, Department of Emergency Medicine, New York, New York ‡ NYC Health + Hospitals/Elmhurst, Department of Surgery, Queens, New York § Icahn School of Medicine at The Mount Sinai Hospital, Department of Surgery, New York, New York o Co-authors

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted September 29, 2025; Revision received April 24, 2026; Accepted April 12, 2026 Electronically published September 24, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.52977

Introduction: Global temperatures are increasing because of climate change, affecting human health. Elevated ambient temperature has been shown to increase rates of trauma presentations in emergency departments and to increase antisocial behavior, such as violent crime. To better understand how to reduce the burden on trauma hospitals, we must better understand the relationship between ambient temperature, trauma patients, and intentional injury. We sought to examine the relationship between trauma rates and minimum and maximum daily temperatures and assess whether the assault trauma mechanism had the strongest association between weather and trauma rates. Methods: We conducted a retrospective cohort study of full and partial trauma team activations that presented to a Level I trauma center in New York from 2012 to 2019, inclusive. Daily maximum and minimum temperatures were divided into quintile ranges. Traumas were classified by injury type and mechanism as either unintentional, assault, or intentional self-harm. We used generalized linear models with a Poisson distribution to examine the relationship between maximum and minimum temperature ranges and trauma rates, controlling for precipitation. Results: Increasing daily minimum and maximum temperatures positively correlated with increasing trauma activations. While all trauma types increased with increasing temperature, assault traumas showed the highest rate of increase (P < .001). Compared to the lowest temperature quintile (< 46 °F), the two highest maximum temperature quintiles (> 73 °F and 83 °F) showed an increase in assault rates of 83% and 65% (incident rate ratio 1.83 [95% CI, 1.46–2.29] and 1.65 [95% CI, 1.32–2.07], respectively). Conclusion: Trauma rates have a positive association with increasing ambient temperature rates. This temperature effect is largest among the assault group, suggesting that as temperatures continue to increase, so too will traumas that are the result of interpersonal violence. [West J Emerg Med. 2026;27(6.1)163–173.]

INTRODUCTION The ongoing climate crisis is changing both weather patterns and our society. Initial estimates from the 2015 Paris Agreement predicted that the planet will warm to 1.5 ºC above Volume 27, Supplement: November 2026

pre-industrial levels between 2030 and 2052.1 However, data shows that the average temperature in 2024 reached 1.5 ºC above pre-industrial levels, suggesting that the 1.5–2 ºC limit of the Paris Agreement may be reached sooner.2 In 2024,

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weather disasters cost US $402 billion globally; 2024 was also noted as the hottest year on record for the contiguous United States.2,3 The changes in our climate and monetary costs of weather events may impact processes as disparate as the food supply and transportation needs.1 Elevated temperatures have important impacts on human behavior. Increasing temperatures have been shown to correlate with increases in civil conflict in Sub-Saharan Africa,4 online hate-speech in the United States,5 and violent crime rates in the United States and globally.6–9 A meta-analysis of studies of temperature and violent crime in 2024 found an increase of 9% in risk of violent crime for every 10 ºC increase in mean temperature,6 and temperature has been shown to have a greater association with violent crime than overall crime.7 Temperature changes have also been shown to influence trauma hospitals’ admission rates. Trauma rates are noted to increase substantially in summer months.10–14 This is likely in part due to higher temperatures, as rates of adult and pediatric trauma presentations increase with increasing maximum temperatures.10,11,15–23 Total emergency department (ED) presentations have been shown to increase with increasing temperature,24–26 as well as the proportion of those visits made up of trauma patients.27 Given the increase in trauma admissions, civil unrest, and violence when temperatures increase, it is likely that acts of violence are a significant contributor to the increase in traumatic injuries. In this study, we performed a retrospective analysis of records of ED visits from the trauma database of a Level I trauma center in a large urban center and National Oceanic and Atmospheric Administration (NOAA) climate data to determine whether trauma rates increased with increasing ambient temperatures, and whether temperature-related effects on trauma rates were driven by intentional injuries (either violence or self-harm). Our hypothesis was that as ambient temperatures increase, trauma rates increase, with intentional injuries driving a large portion of this increase. METHODS Data Collection After institutional review board approval for informed consent exemption waiver was obtained, we conducted a retrospective cohort study28–30 of all full and partial ED trauma activations at Elmhurst Hospital, an urban Level I trauma center in New York, from January 2012–December 2019, inclusive. Inclusion criteria included patients ≥ 18 years of age who arrived as full and partial trauma activations. Consistent with performance improvement methodology and best practices in trauma literature, patients who arrived dead (no discernible blood pressure, pulseless, apneic) were excluded; these patients are considered to have low-to-no chance of survival, and their inclusion could introduce potential confounding variability and distract from targeting quality improvement opportunities.31–33 We excluded from the analyses records with missing data for injury date and time or Western Journal of Emergency Medicine

Population Health Research Capsule What do we already know about this issue? Trauma rates are impacted by weather patterns, with higher rates during warmer weather. What was the research question? Does the assault trauma mechanism have the strongest association between weather and trauma rates? What was the major finding of the study? Compared to the lowest temperature quintile (< 46 ºF), the two highest temperature quintiles (> 73 ºF and 83 ºF) showed an increase in assault rates of 83% and 65% (incident rate ratio 1.83 [1.46–2.29] and 1.65 [1.32–2.07], respectively). How does this improve population health? We found an association between rates of assault trauma and increasing temperature, which may reflect the need to focus on intervention, as the climate changes.

injury mechanism. We collected data from our trauma registry, which contains extensive clinical data for all trauma patients who present to our ED. This includes Injury Severity Scale (ISS) and blood alcohol level, metrics required by the American College of Surgeons for trauma patients at Level I trauma centers.34,35 Trauma activation is defined at our institution as the alerting of the trauma team of emergency physicians and nurses and trauma surgery physicians when a patient is deemed to have moderate or severe risk of injury based on institutional trauma guidelines. Patients meeting red trauma criteria led to full trauma team activations, while patients meeting yellow trauma criteria led to partial activations (Supplemental Figure 1). Partial trauma activations include emergency and trauma surgery physicians, while full activations include physicians from orthopedics, anesthesiology, the surgical intensive care unit, and operating room staff. Weather data was obtained from the NOAA climate database for the LaGuardia Airport station, located approximately 2.3 miles from our hospital. Data included daily high (maximum) and low (minimum) temperatures in degrees Fahrenheit and daily precipitation in inches. Classification of Trauma Intent of Injury We classified each trauma record into Centers for Disease

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Mosley et al. Control and Prevention (CDC)-defined intent of injury categories36 using their assigned Centers for Medicare & Medicaid Services (CMS) International Classification of Diseases (ICD) mechanism billing codes from both the Ninth Revision, Clinical Modification (ICD-9-CM)37 and Tenth Revision (ICD-10-CM) documentation.38 Specifically, for each record, primary and secondary mechanism ICD-9-CM codes (from the icd.data R package39) and ICD-10-CM codes (useicd10cm R package39) codes were evaluated and matched to determine trauma mechanism and intent type. These ICD codes were then pattern-matched to external cause-of-injury codes (E-codes)40,41 and then mapped to intent categories using the CDC’s External Cause of Injury Mortality Matrix.42,43 The intent of injury categories are as follows: 1) Unintentional; 2) Intentional Self-Harm; 3) Assault; 4) Legal Intervention/War Operations; and 5) Undetermined. Unmatched records were labeled as unspecified or other. We focused on Unintentional, Intentional Self-Harm or Assault injuries for subsequent analyses. Injury type (blunt, penetrating, burn) was precoded in our institution’s trauma registry based on ICD-10 E-codes as determined by the New York State Trauma Registry.44 Descriptive Analyses Patient and trauma characteristics were summarized using descriptive statistics. For continuous variables, we compared between-group medians using the non-parametric Wilcoxon rank-sum test for two groups and the nonparametric KruskalWallis rank-sum test for three or more groups. Categorical variables were checked with the chi-squared test, or Fisher exact test if the number of observations was < 20. Spearman correlation method was used to assess the nonlinear relationship between daily maximum (TMAX) and minimum temperatures (TMIN). We examined the relationship between trauma frequency and temperature changes daily and seasonally over the time period using scatterplots. Regression Analyses To quantify the relationship between temperature and trauma frequency, we used generalized linear models with a Poisson distribution using TMAX and TMIN as categorical predictors (divided into quintiles based on empirical cut points from the full dataset) and mean number of daily trauma cases as the outcome, controlling for precipitation. Reference quintiles were 15 °F to 46 °F for TMAX and 1 °F to 46 °F for TMIN. Sensitivity analyses were conducted by repeating the regression analyses on subgroups of sex, race and ethnicity as reported in the data. We determined incidence rate ratios (IRR), their 95% confidence intervals, and P values for all models. Statistical Analyses Throughout our analysis, statistical significance was defined as P < .05 for significance at the 95% CI, P < .01 at the 99% CI, and P < .001 at the 99.99% CI. All tests were two-tailed. We analyzed all data using R v4.4.2 (“Pile of Leaves,” released Volume 27, Supplement: November 2026

October 31, 2024) (R Foundation for Statistical Computing, Vienna, Austria) in the RStudio integrated development environment v2025.05.1+513 (Posit PBC, Boston, MA). RESULTS A total of 5,113 trauma activations met criteria during the study period, of which 80% were unintentional, 16.7% assaults, and 3.3% from intentional self-harm. Table 1 shows the sample characteristics overall and by trauma intent. There were three times as many men as women in the entire cohort, with the majority of assault patients being men (92%). Differences in sex were statistically significant across intent types (P < .001). Median age was 37.1 years, with the assault group being the youngest (29.3 years) and the unintentional group the oldest (40.1 years). The majority of patients were classified as “other” for race (60%). White patients comprised about one-fifth of both unintentional and self-harm groups. In contrast, Black patients were the second most common demographic group among assault cases (14%). Across all groups, non-Hispanic patients were more numerous than Hispanic patients, comprising 66% of patients in both the unintentional and self-harm groups and 53% of those in the assault trauma group. Most trauma activations were partial activations (72%). Proportions were similar for unintentional traumas, with only 23% being full trauma activations. Assault and intentional self-harm were twice as likely to result in a full trauma team activation than unintentional traumas (P < .001). On average, patients in the assault and self-harm groups had shorter ED length of stay than those in the unintentional trauma group (P < .001). Patients in the unintentional trauma and assault groups had comparable rates of discharge from the ED (42% and 47%, respectively) and death in the ED (1.2% and 1.4%, respectively). However, intentional self-harm trauma activations significantly differed from other groups, with only 35% being discharged from the ED and trauma patients who intentionally self-harmed being nearly three times as likely to die in the ED. Notably, trauma patients in the assault group had higher blood alcohol levels than other groups (P < .001). Table 2 shows sample composition by trauma injury type and mechanism. Overall, most patients experienced blunt trauma (84%), although assault victims were twice as likely to have penetrating trauma (68% of assault patients) than blunt trauma (32%). Motor vehicle crashes and falls comprised 57% of all traumas and were the most frequent mechanisms among unintentional injuries, followed by pedestrian injuries (7.1%), bike crashes (5.6%), nontraffic motor vehicle injuries (5.6%), and environmental injuries (5.6%). Assault patients primarily had cutting/piercing injuries (64%), were struck (12%), or had firearm injuries (9.5%). Intentional self-harm cases mostly involved cutting/piercing injuries (54%), suffocation (19%), and falls (13%). Figure 1 shows regional weather variations over the study

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Table 1. Patient sample characteristics by primary injury intent in a study examining the relationship between trauma rates and minimum and maximum daily temperatures. Overall N = 5,1131

Unintentional n = 4,0881

Assault n = 8551

Intentional Self-Harm n = 1701

P value2,3

37.1 (22.3)

40.1 (23.5)

29.3 (11.9)

34.9 (15.6)

<.0001***

Male

3,847 (75%)

2,925 (72%)

786 (92%)

136 (80%)

Female

1,265 (25%)

1,163 (28%)

69 (8.1%)

33 (20%)

Characteristic Age Sex

.0005***

Race

.0005***

Other

2,932 (60%)

2,244 (57%)

593 (73%)

95 (59%)

White

1,024 (21%)

918 (23%)

72 (8.9%)

34 (21%)

Asian

481 (9.8%)

437 (11%)

30 (3.7%)

14 (8.7%)

Black

438 (9.0%)

305 (7.8%)

116 (14%)

17 (11%)

American Indian

9 (0.2%)

7 (0.2%)

1 (0.1%)

1 (0.6%)

Native Hawaiian or Other Pacific Islander

1 (<0.1%)

0 (0%)

Ethnicity

.0035**

Non-Hispanic

2,980 (64%)

2,467 (66%)

410 (53%)

103 (66%)

Hispanic

1,674 (36%)

1,257 (34%)

365 (47%)

52 (34%)

Not applicable

2 (<0.1%)

0 (0%)

ISS

4.0 (10.6)

5.0 (10.8)

2.0 (9.1)

4.0 (11.7)

Trauma team activation level

<.0001*** .0005***

Partial, second level response

3,667 (72%)

3,163 (77%)

428 (50%)

76 (45%)

Full team activation, highest level response

1,446 (28%)

925 (23%)

427 (50%)

94 (55%)

ED LOS (hours)

7.3 (31.7)

7.6 (35.3)

6.1 (7.3)

4.2 (6.9)

ED disposition

<.0001*** .0005***

Admitted

2,701 (53%)

2,184 (53%)

425 (50%)

92 (54%)

Discharged to home or self-care (routine discharge)

2,198 (43%)

1,736 (42%)

402 (47%)

60 (35%)

Died in ED

67 (1.3%)

48 (1.2%)

12 (1.4%)

7 (4.1%)

Transferred to another hospital ED

64 (1.3%)

59 (1.4%)

5 (0.6%)

0 (0%)

Died on arrival

38 (0.7%)

32 (0.8%)

3 (0.4%)

3 (1.8%)

Died within 15 minutes

27 (0.5%)

16 (0.4%)

5 (0.6%)

6 (3.5%)

Transferred to another hospital in-patient

18 (0.4%)

13 (0.3%)

3 (0.4%)

2 (1.2%)

Alcohol level (mg/dL)

0.0 (129.6)

0.0 (130.0)

132.0 (125.0)

0.0 (103.4)

<·0001***

Median (SD); n (%) Kruskal-Wallis rank sum test 3 *P < .05; **P < .01; ***P < .001 ED, emergency department; ISS, Injury Severity Scale; LOS, length of stay; mg/dL, milligram per deciliter. 1 2

period. The TMAX and TMIN varied seasonally, with peaks in summer months and troughs in winter months (Figure 1A). Daily TMAX and TMIN showed a strong correlation with each other (Spearman ⍴ = 0.96, P < .001). Conversely, there was high variability in precipitation across the study period, ranging from 0–8 inches, without a clear seasonal pattern (Figure 1B). Notably, months with heavier precipitation became more frequent beginning in 2017. There was no significant correlation between TMAX or TMIN and precipitation (Spearman ⍴ = Western Journal of Emergency Medicine

-0.03, P = .15). Figure 1C illustrates the distribution of daily TMAX and TMIN, showing that both have a bimodal distribution of values, corresponding to seasonal extremes. The TMAX skews left with a median around 65 °F, while TMIN skews right with a median around 51 °F. Figure 2 shows the relationship between temperatures and mean daily trauma counts. Figure 2A shows the temperaturetrauma relationship over the eight-year study period, fitted using locally estimated scatterplot smoothing (LOESS) curves

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Table 2. Summary of injuries and mechanisms of cohort in a study examining the relationship between trauma rates and minimum and maximum daily temperatures. Overall N = 5,1131

Unintentional n = 4,0881

Assault n = 8551

Intentional Self-Harm n = 1701

Blunt

4,284 (84%)

3,926 (96%)

273 (32%)

85 (50%)

Penetrating

798 (16%)

133 (3.3%)

582 (68%)

83 (49%)

Burn

30 (0.6%)

29 (0.7%)

0 (0%)

1 (0.6%)

Unknown

1 (0%)

0 (0%)

1 (0%)

Motor vehicle-Traffic

1,576 (31%)

1,571 (38%)

3 (0.4%)

2 (1.2%)

Fall

1,336 (26%)

1,312 (32%)

2 (0.2%)

22 (13%)

Cut/pierce

663 (13%)

26 (0.6%)

546 (64%)

91 (54%)

Pedestrian, other

291 (5.7%)

291 (7.1%)

0 (0%)

Pedal cyclist, other

230 (4.5%)

230 (5.6%)

0 (0%)

Motor vehicle-nontraffic

228 (4.5%)

228 (5.6%)

0 (0%)

Natural/environmental

228 (4.5%)

228 (5.6%)

0 (0%)

Struck by/against

156 (3.1%)

52 (1.3%)

104 (12%)

0 (0%)

Firearm

91 (1.8%)

5 (0.1%)

81 (9.5%)

5 (2.9%)

Other specified, not elsewhere classifiable

84 (1.6%)

2 (<0.1%)

72 (8.4%)

10 (5.9%)

Other transport

67 (1.3%)

66 (1.6%)

1 (0.1%)

0 (0%)

Unspecified

55 (1.1%)

14 (0.3%)

41 (4.8%)

0 (0%)

Suffocation

35 (0.7%)

2 (<0.1%)

0 (0%)

33 (19%)

Other specified, classifiable

22 (0.4%)

17 (0.4%)

5 (0.6%)

0 (0%)

Fire/burn

21 (0.4%)

18 (0.4%)

0 (0%)

3 (1.8%)

Poisoning

7 (0.1%)

7 (0.2%)

0 (0%)

Machinery

6 (0.1%)

0 (0%)

Other land transport

5 (<0.1%)

1 (<0.1%)

0 (0%)

4 (2.4%)

Overexertion

5 (<0.1%)

5 (0.1%)

0 (0%)

Hot object/substance

4 (<0.1%)

0 (0%)

Drowning/submersion

2 (<0.1%)

0 (0%)

Bites and stings, nonvenomous

1 (<0.1%)

0 (0%)

Characteristic Injury type

Mechanism type

n (%)

to smooth over day-to-day variability. There was a nonlinear positive association between temperature and trauma frequency, especially in the mid-temperature range. For TMIN, there is an initial downward trend in trauma frequency as temperature increases from 0 to 25 °F, followed by an uptrend in frequency, peaking at approximately 75–80 °F. The TMAX exhibited a similar pattern, with trauma frequency being lower at cooler temperatures, increasing steadily as temperatures increase up to 75–80 °F range and then leveling off past 80 °F. Daily total trauma counts ranged from 0-10 daily and followed similar seasonal patterns as temperature (Figure 2B). Figure 3 shows the relationship between daily temperatures and trauma frequency stratified by intent type. Volume 27, Supplement: November 2026

For unintentional traumas, frequency remained relatively stable across temperature ranges, with only a slight increase at higher temperatures for both TMAX and TMIN. For assault injuries, there was a positive association between temperature and frequency, with higher assault rates at warmer temperatures (30–65 °F). Intentional self-harm rates were generally low and stable across the temperatures, with some isolated spikes at higher temperatures. Table 3 and Figure 4 shows regression results for TMAX and TMIN quintiles on mean daily number of traumas by trauma intent type (controlling for precipitation). Incident rate ratios increased as TMAX increased. Total trauma frequency increased with TMAX, reaching a 27% increase in the highest

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Figure 1. Weather trends in Queens, New York, from 2012–2019.

temperature quintile (83 °F to 101 °F) compared to the coolest temperatures (P < .001). Assault trauma exhibited the most dramatic temperature-dependent pattern, with rates increasing substantially across temperature quintiles. There was a 39% increase at 47–59 °F (P < .01), 49% increase at 60 °F–72 °F (P < .001), 83% increase at 73 °F–82 °F (P < .001), and 65% increase at 83 °F–101 °F (P < .001). The greatest increase in the fourth quintile (73 °F–82 °F) is consistent with the decline in rates above 80 °F seen in Figure 3. Unintentional trauma showed a more moderate temperature effect, with the highest quintile demonstrating a 23% increase in rates (P < .001). In contrast, self-harm trauma rates decreased with increasing temperatures (IRR < 1.0, P ≥ .05). Results were similar for TMIN, with a 21% and 76% increase in overall and assault trauma frequency, respectively, in the highest temperature quintile (69 °F to 86 °F) compared to the coolest temperatures (P < .001). Unintentional trauma again showed a more moderate but statistically significant increase, while self-harm showed a decrease that was not significant. For all models, precipitation showed no significant effect on any trauma type nor overall (IRRs ~ 1.00, P ≥ .05). Sensitivity Analyses Regression analyses stratified by sex, race and ethnicity were conducted for subgroup sensitivities (Supplementary Tables 1 and 2, respectively). Note, there were no statistically significant associations between precipitation and injury for any subgroups (P ≥ .05). Sex

Men showed increased assault risk at higher TMAX, with the 73 °F–82 °F range demonstrating a statistically significant Western Journal of Emergency Medicine

Mosley et al.

Figure 2. Variation of trauma frequency with temperatures in a study examining the relationship between trauma rates and minimum and maximum daily temperatures.

42% increase in assault incidents (P < .01), and risk decreasing thereafter (Supplementary Table 1). Risk of self-harm incidence decreased by 48% in this same temperature range (P < .05). There were similar increases in assault risk as TMIN increased, especially in the 46 °F–86 °F ranges (P < .05). There were no statistically significant patterns for unintentional or overall trauma rates (P ≥ .05). Women showed similar trends to men, however there was a nearly nine-fold increase in assault rates in the highest temperature range (P < .001) Ethnicity Hispanic patients saw some notable temperature-injury associations, with IRRs of assaults increasing up to TMAX of 82 °F (Supplementary Table 2). A TMAX of 73 °F–82 °F produced the strongest association with assault risk, showing an 88% increase in risk (P < .001). Conversely, TMAX was protective against self-harm, with a significant reduction of 72% in risk in the 47 °F–59 °F TMAX range (P < .05). Results were similar for TMIN. The non-Hispanic population exhibited more moderate temperature-injury associations, with increasing but not statistically significant IRRs observed as TMAX increased (P ≥ .05). Only TMIN of 58 °F–68 °F showed a statistically significant increase of 52% elevation in risk (P < .01). There were no statistically significant associations across TMAX or TMIN for self-harm traumas (P ≥ .05). DISCUSSION This study investigated the effect of ambient temperature on rates of trauma presentations at a Level I trauma center at a 168

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ethnicity and race.46 Additionally, our finding of an elevated median blood alcohol level in the assault group suggests that alcohol use is a significant risk factor for assault.47–50 Finally, alcohol use in our patient population was not correlated with unintentional trauma that may be frequently associated with alcohol, such as motor vehicle crashes or falls.

Figure 3. Variation of mean daily number of traumas with temperature by trauma intent subtype.

large, urban hospital. We hypothesized that not only would trauma rates increase as temperatures increase, but that this temperature-related increase would be driven by assaults, as opposed to unintentional injuries or intentional self-harm. Our results suggest that temperature is positively correlated with overall trauma volume, suggesting a temperature-related increase in trauma incidence. This could reflect behavioral or environmental changes such as more people being active outdoors, heat-related stressors, or seasonal risk factors. Further, our regression analysis illustrates that maximum daily temperatures above 83 °F may reflect a temperature threshold beyond which trauma risk does not continue to rise, again possibly due to behavioral or environmental limits. Further, assault trauma frequency showed a strong positive relationship with temperature in dose-dependent manner,45 while self-harm remains unaffected by temperature variations.8,9 This suggests that heat is a specific risk factor for interpersonal violence. Our sensitivity analyses showed a clear sex disparity in weather-injury relationships, with women showing substantially greater sensitivity to temperature-related assault risk. Similarly, Hispanic populations demonstrated substantially greater sensitivity to temperature variations than their non-Hispanic counterparts, particularly regarding assault risk during warmer conditions. This suggests potential vulnerability factors that may include social, economic, or environmental circumstances that interact with weather patterns. We found that rainfall patterns did not meaningfully influence overall and specific injury rates in this population. Precipitation effects remained minimal across subgroups of sex, Volume 27, Supplement: November 2026

Strengths This study has several strengths. Firstly, by examining an eight-year period, we avoided drawing conclusions about climate patterns based on anomalous individual years. This approach prevented distortions from irregular weather events such as El Niño,51 specific disasters such as Hurricane Sandy in 2012,52 or the volume changes caused by the COVID-19 pandemic that began in 2019, when Elmhurst Hospital became one of the most overwhelmed hospitals in the United States.53 Second, we classified traumas by both intent and mechanism, going beyond the common practice of using only broad categories like blunt, penetrating, or burn injuries. This detailed classification allowed us to better understand causality, which can inform more targeted prevention strategies. Our findings revealed that seasonal increase in traumas resulted primarily from rising assault rates; community and governmental violence prevention programs could help reduce this pattern. Additionally, that motor vehicle collisions were the most frequent injury mechanism overall suggests that street redesigns and traffic calming measures in our hospital’s catchment area could significantly reduce trauma cases. Third, our use of temperature ranges rather than absolute temperature values represents a methodologically sound approach that accounts for the nonlinear nature of temperatureinjury relationships and provides more robust statistical power by aggregating observations across meaningful temperature categories rather than treating temperature as a continuous variable with potentially sparse data points at extreme values. Clinical Implications Our findings suggest that the rising global temperatures of climate change may impact the practice of emergency medicine by increasing trauma rates and changing trauma patterns. With patients now exposed to twice as many heatwave days as they would have experienced in 1985– 2005,54 the effects of high temperatures on trauma rates is likely to worsen in the coming years. This may warrant seasonal staffing adjustments in trauma centers to account for the greater numbers of trauma presentations. Staffing needs and resource utilization at trauma hospitals is likely to significantly contribute to the estimated US $820 million annual health costs in the U.S. from climate change, and the US $1.1 trillion burden on healthcare systems due to climate change predicted by 2050 by the World Economic Forum.55,56 Our results show that these changes may be driven by trauma resulting from interpersonal violence, suggesting a clear target for intervention. The differential patterns in the

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Table 3. Effect of minimum and maximum daily temperature quintiles on mean daily number of traumas. Predictor

Total

Assault

Unintentional

Self-Harm

IRR (95% CI)

Maximum Temperature Reference: 15 °F to 46 °F

—

47 °F to 59 °F

1.15 (1.05–1.26)**

1.39 (1.10–1.76)**

1.14 (1.03–1.26)**

0.67 (0.42–1.07)

60 °F to 72 °F

1.15 (1.05–1.25)**

1.49 (1.18–1.87)***

1.12 (1.01–1.23)*

0.79 (0.50–1.23)

73 °F to 82 °F

1.16 (1.06–1.27)**

1.83 (1.46–2.29)***

1.08 (0.98–1.19)

0.66 (0.40–1.06)

83 °F to 101 °F

1.27 (1.17–1.39)***

1.65 (1.32–2.07)***

1.23 (1.12–1.36)***

0.88 (0.57–1.36)

—

Minimum Temperature Reference: 1 °F to 35 °F 36 °F to 45 °F

1.13 (1.03–1.23)**

1.34 (1.06–1.70)*

1.12 (1.01–1.23)*

0.73 (0.45–1.15)

46 °F to 57 °F

1.11 (1.01–1.21)*

1.60 (1.27–2.01)***

1.05 (0.95–1.16)

0.84 (0.53–1.31)

58 °F to 68 °F

1.25 (1.14–1.36)***

1.78 (1.42–2.23)***

1.20 (1.09–1.32)***

0.63 (0.38–1.02)

69 °F to 86 °F 1.21 (1.11–1.32)*** 1.76 (1.41–2.21)*** 1.14 (1.04–1.26)** 0.93 (0.60–1.44) Notes: 1 Temperatures were divided into quintiles based on their daily distribution. The reference range is the first quintile. IRR for this quintile is standardized to 1.00 (no effect). 2 Statistical significance: * indicates P value < .05, ** indicates P value < .01, *** indicates P value < .001. IRR, incident rate ratios.

sensitivity analyses have significant implications for targeted public health interventions, underscoring the critical importance of incorporating racial and ethnic demographics into environmental health interventions targeting temperaturerelated injury prevention. These effects reflect complex interactions between environmental exposures, socioeconomic factors, and community-level vulnerabilities that require further investigation to develop effective, culturally appropriate interventions. Research Implications Our study contributes to trauma and climate science literature by showing that increasing rates of trauma occur as outdoor temperatures increase, driven largely by assaults, as opposed to alcohol-related motor vehicle crashes, falls, or self-harm, with variable patterns in different demographic groups. Further research is required to better understand causal factors contributing to differential trauma vulnerability with increasing temperature across demographic subgroups, and to assess the role for and efficacy of different violence prevention interventions. LIMITATIONS The findings of our study must be interpreted within the context of its limitations. As a single-center study conducted in a large urban environment, our findings may not be generalizable to other trauma hospital settings. Moreover, New York City’s unique characteristics—including high population density, extensive public transit, and strict guncontrol laws—likely influenced our results in ways that differ Western Journal of Emergency Medicine

from other locations. The impact of local gun laws is particularly evident in our data. Nationally, there were over 39,000 fatal and 82,000 nonfatal gunshot wounds in 2019 alone.57 In contrast, only 81 patients in our sample were injured by firearms in our eight-year study period. Our findings may be further explained by Queens having the lowest per capita gunshot wounds among New York City’s boroughs.58 This limits our study’s generalizability to other areas with different crime profiles. Our analysis is also limited by using clinician-assigned ICD coding to determine injury mechanisms. This is an inherently subjective process and requires clinician’s judgment and discretion when assigning ICD codes. Additionally, it is likely that for many patients only a single ICD code was selected when multiple may have been appropriate. Race and ethnicity in our database are categorized according to National Trauma Standard Data Dictionary. This framework lacks nuance,59 and includes an “other” race category that may mask distinct injury patterns among diverse populations. In racially and ethnically diverse neighborhoods, many people may consider themselves multiracial or not otherwise fit well into a single racial demographic. Ideally, race is determined by patient self-report; however, in a trauma setting where patients are often in extremis or unresponsive, this is often not possible. Additionally, the American Indian and Native Hawaiian/other Pacific Islander participants were excluded from analysis due to insufficient sample sizes. These constraints may obscure population-specific temperatureinjury relationships and reduce generalizability to other

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Address for Correspondence: Grace E. Mosley, MD, PhD, Icahn School of Medicine at Mount Sinai, Department of Emergency Medicine, 3 E 101st St, New York, NY 10029. Email: grace.mosley@mountsinai.org. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Mosley et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

Figure 4. Forest plot of effect of temperatures on mean daily number of traumas by intent.

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CONCLUSION Increased temperature is associated with an increase in overall trauma incidence, with a potential peak or saturation point in the upper temperature ranges. Trauma rates showed seasonal variation, with more trauma presentations in warmer months, with the largest increase in trauma rates among intentional injuries. As the climate warms, there is a risk for increasing trauma presentations secondary to violence. Thus, both hospital staffing models and public health interventions must anticipate this change. ACKNOWLEDGMENTS Thank you to the residents in the Emergency Medicine Program at the Mount Sinai/Elmhurst program for your continued support. Volume 27, Supplement: November 2026

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54. Romanello M, Napoli CD, Green C, et al. The 2023 report of the

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Lancet Countdown on health and climate change: the imperative for

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a health-centred response in a world facing irreversible harms.

February 1, 2026. 45. Kubo R, Ueda K, Seposo X, et al. Association between ambient

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temperature and intentional injuries: a case-crossover analysis using

human health. 2024. Available at: https://www.weforum.org/

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2021;774:145511. 46. Zibners LM, Bonsu BK, Hayes JR, et al. Local weather effects on

health/. Accessed September 19, 2025. 56. NRDC. Report: health costs from climate change and fossil fuel

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org/press-releases/report-health-costs-climate-change-and-fossil-fuel-

47. Scott KD, Schafer J, Greenfield TK. The role of alcohol in physical assault perpetration and victimization. J Stud Alcohol.

pollution-tops-820-billion-year. Accessed September 19, 2025. 57. Miller GF, Barnett SBL, Florence CS, et al. Costs of fatal and nonfatal

1999;60(4):528-536.

firearm injuries in the U.S., 2019 and 2020. Am J Prev Med.

48. Ray JG, Turner L, Gozdyra P, et al. On-premise alcohol establishments and ambulance calls for trauma, assault, and

2024;66(2):195-204. 58. Agarwal M, Idaikkadar N, Weiss D. Epidemiology of gunshot-related

intoxication. Medicine (Baltimore). 2016;95(19):e3669.

injuries in NYC emergency departments from 2004-2014. Online J

49. Nepal S, Kypri K, Tekelab T, et al. Effects of extensions and restrictions in alcohol trading hours on the incidence of assault and

Public Health Inform. 2015;7(1):e7. 59. Nahmias J, Zakrison TL, Haut ER, et al. Call to action on the

unintentional injury: systematic review. J Stud Alcohol Drugs.

categorization of sex, gender, race, and ethnicity in surgical research.

2020;81(1):5-23. 50. Char S, Sharma B, Arnold M, et al. Role of blood alcohol level on the

J Am Coll Surg. 2021;233(2):316-319. 60. Coco A, Jacklitsch B, Williams J, et al. Criteria for a recommended

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51. Chen D, Cane MA, Kaplan A, et al. Predictability of El Niño over the past 148 years. Nature. 2004;428(6984):733-736.

106.pdf. Accessed February 3, 2026. 61. Budd GM. Wet-bulb globe temperature (WBGT)--its history and its

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limitations. J Sci Med Sport. 2008;11(1):20-32.

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Climate Change: Original Research

Partial Immersion Using Body Bags for Exertional Hyperthermia: A Randomized Crossover Study Diane Zashin, MAT, LAT, ATC* Xiujing Zhao, MS† Luzita Vela, PhD, LAT, ATC‡ Elizabeth Parke, PhD, ATC‡ Ramon Ylanan, MD§ Brendon P. McDermott, PhD, ATC‡

*Wellness Workdays, Hingham, Massachusetts † University of Arkansas, Heat and Hydration Optimization (H2O) Lab, Fayetteville, Arkansas ‡ University of Arkansas, Department of Health, Human Performance and Recreation, Fayetteville, Arkansas § University of Arkansas for Medical Sciences, Department of Orthopaedics and Sports Medicine, Fayetteville, Arkansas

Section Editor: Mark I. Langdorf, MD, MHPE Submission history: Submitted February 12, 2026; Revision received June 17, 2026; Accepted May 21, 2026 Electronically published September 5, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.62965

Introduction: Recent recommendations suggest emergency medical personnel should consider rapid whole-body cooling for heat stroke patients. Cold-water immersion maximizes cooling rate and subsequent outcomes following heat stroke. Body bags filled with ice and water may provide portable, accessible partial cold-water immersion for this setting. The purpose of this study was to determine whole-body cooling rates when using body bags to facilitate partial cold-water immersion to treat exertional hyperthermia. Methods: A total of 9 healthy participants (8 male; mean [SD] age, 24 [4] years; height, 175 [7] cm; body mass, 83.6 [21.6] kg) completed our randomized-crossover field study. Following hydration verification, participants completed a self-paced 400 warm-up run, 1,609 m run, and 10-m sprints until rectal temperature (T-rec) reached 39.2 °C or volitional exhaustion. Following exercise, participants were cooled for a maximum of 30 minutes lying supine in the shade (control; CON) or in body bags filled with 20 gallons of ice water (5.2 [1.6] °C). Following cooling, participants sat upright for a 15-minute recovery. T-rec and heart rate (HR) were taken throughout exercise, every minute of cooling, and every 5 minutes of recovery. Participants completed both trials separated by 1 week in random order. Results: Wet bulb globe temperature between trials was not significantly different (grand mean, 28.43 [1.03] °C; P = .73). There was no difference in participant maximum T-rec (body bag, 38.98 [.23] °C; CON, 38.93 [.39] °C; P = .45); HR (body bag, 183 [14] beats per minute [bpm]; CON, 189 [13] bpm; P = .21); rating of perceived exertion (P >.99); thirst (P = .62); or thermal sensation (P = .73) during exercise. Fluid consumed (P = .40), body mass change (P = .90), 400 m run times (P = .19) and 1,609 m run times (P = .17) were no different between trials. Whole-body cooling rate for body bag was .102 (.04) °C/min, whereas CON produced a cooling rate of .040 (.04) °C/min (95% CI, .030-.095; P = .002). Total cooling time was significantly faster (13.2 (5.8) min) with BB compared to CON (27.6 (4.2) min; 95% CI, 9.2-19.5; P = .002). Conclusion: In clinical settings where full-body cold-water immersion is not feasible, or during emergency transport, partial immersion via body bags offers acceptable cooling rates for hyperthermic patients. Emergency medical personnel could apply these data for support in updating heat stroke protocols to include partial immersion via body bag during transport, or immediately upon emergency department arrival. [West J Emerg Med. 2026;27(6.1)174–180.]

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Zashin et al. INTRODUCTION Heat stroke represents the most serious heat illness, with potentially fatal consequences unless rapid recognition and treatment are initiated soon after onset.1-4 Clinical recommendations for the management of exertional heat stroke demonstrate overwhelming success when early recognition and effective treatment are initiated.5 Evidencebased recognition and management could improve outcomes within military and emergency department (ED) settings. The Army and Marine Corps have higher incidences of exertional heat stroke with .67 per 1,000 person-years and .72 per 1,000 person-years, respectively.6 However, the feasibility of having cold-water immersion tubs available for all training is limited.6 In EDs, the recognition and treatment of either classic or exertional heat stroke also present challenges.7,8 In one analysis, 5.4% of those admitted to the hospital for heat illness were diagnosed with heat stroke.9 Those who were diagnosed had an admittance rate of 62.0%.8 In some areas, heat stroke cases represent 28.3% of all admissions and 77% of all deaths for heat illness cases.8 These numbers are the result of medical personnel on-site not following a “cool first, transport second” protocol, as well as a lack of resources for rapid cooling upon ED arrival.9,10 Military and ED settings include specific barriers for compliance with established, recommended practices for exertional heat stroke.6 Following rapid recognition in the field, effective treatment should be applied to avoid negative outcomes or sequelae.10-12 Data strongly suggest 100% fatality avoidance with whole-body cold-water immersion.5,10 In emergent situations, the standard of care is to confirm diagnosis (core temperature > 40.5 °C with central nervous system dysfunction) and immerse the patient. Recent prehospital care recommendations echo these guidelines.1,11,12 Treatment for classic heat stroke, however, lacks consistent supportive data.8,12 Recent cases support aggressive cooling for classic heat stroke patients as well.13-15 In either case, if lifesaving treatment involves reducing hyperthermia as quickly as possible, data support the use of cold-water immersion.5,13 Further, to facilitate effective cooling, using the coldest water possible and including water circulation should be included. Recent cases demonstrate successful outcomes for patients with exertional or classic heat stroke treated with cold-water immersion.16,17 Common issues reported include the logistics of transporting a large rigid tub in various environments and having access to water and ice volumes necessary for effective cold-water immersion. Both venues present a unique opportunity based on likely availability of body bags. Since cold-water immersion in a large rigid tub— the current gold standard for whole-body cooling17—is not always feasible at the site of heat stroke or during transport, body bags present a conduit to perform partial immersion.4,13 According to McDermott et al,17 ideal cooling rates for patients with exertional heat stroke are ≥ .155 °C/min, acceptable cooling rates are those between .078 °C/min and .154 °C/min, and Volume 27, Supplement: November 2026

Population Health Research Capsule What do we already know about this issue? Cold-water immersion provides the fastest cooling rates for hyperthermic individuals and leads to superior patient outcomes. What was the research question? We sought to compare cooling rates for partial immersion in a body bag against lying in the shade for hyperthermic individuals. What was the major finding of the study? Cooling rate for body bags was .102 (.04) °C/ min, whereas lying in the shade was .040 (.04) °C/min (95% .030-.095; P = .002). How does this improve population health? Using a body bag to facilitate whole-body cooling via partial immersion is an option for treating hyperthermic patients in remote settings or during transport.

unacceptable rates are those < .078 °C/min. Data are sparse on cooling rates for hyperthermic individuals in body bags. Studies have been sponsored by a manufacturer of the Polar Life Pod, a body-bag–like device including a pillow and straps (Polar Products, Inc, Stow, OH). Miller and Beck18 reported efficient cooling using the device with water oscillations (between .10 and .17 °C/min) with varying water volumes. Further, Miller and Amaria19 reported ideal cooling with constant oscillations using different water temperatures. Nye et al,20 however, in the only study using the Polar Life Pod without manufacturer funding, found inadequate cooling rates (.04 °C/min). The device may not be a feasible alternative in emergency medical services situations given the cost (> $400); however, traditional body bags, already available in emergency settings, offer a more affordable option. There are case report data supporting cooling with body bags.4,10,13-15 However, without documented support with consistent cooling rates, clinicians should use caution when applying body-bag partial immersion. Offering this alternative could demonstrate an effective cooling modality and improve compliance and patient outcomes. Body bags filled with ice and water, which can fully encase a patient, offer an alternative method of cooling while increasing portability and accessibility for other healthcare professionals (emergency physicians, nurses, etc) and tactical settings. An alternative

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cooling modality that produces acceptable or ideal cooling rates could be used to treat heat stroke in settings where access to cold-water immersion tubs or a commercial cooling device is limited, or not feasible. The purpose of this study was to determine whether partial immersion cooling via body bags offers cooling rates that can be deemed appropriate for cooling hyperthermic patients. Our hypothesis was that partial immersion using a body bag would produce acceptable or ideal cooling rates, making them appropriate to recommend for partial immersion as an alternative treatment when cold-water immersion is not feasible. METHODS We used a randomized, crossover research design in the field to test our hypothesis. The University of Arkansas Institutional Review Board (IRB) approved the study. A total of 13 volunteers were recruited from the University of Arkansas and surrounding area. Each participant completed a medical questionnaire screening to determine fitness and health levels as well as assuring inclusion criteria were met. One participant did not meet inclusion criteria (taking medication known to affect thermoregulation) and was excluded from our study. Participants were included if they self-reported physical activity for at least 30 minutes three times a week and were under the age of 40 years. Participants were excluded if they had suffered from heat illness or exertional heat stroke in the prior three years, were taking medication known to alter fluid balance and/or thermoregulation, were sick at the time of testing, or had suffered a recent orthopedic injury or had exercise restrictions due to an injury. Once clearance was given, participants were randomly assigned to participate in two trial conditions, with the order of treatment for trials randomized using an online random number generator. Researchers and participants were unaware of the trial order for each participant until they arrived and signed their consent form. Based on previous data on cooling rates within our lab, and to garner an estimated power of .80 with significance set to < .05, we calculated that a sample size of eight was required. Participants were randomly assigned to a control (CON) or body-bag cooling trial, with allocation concealed; trials occurred one week apart. We chose not to include a trial of full-body cold-water immersion because those cooling rates have been fully established.17 Further, because cooling rates from exercise hyperthermia match those from case series data, the established cooling rates following exercise hyperthermia are assumed similar to actual heat illness scenarios.4,16,17 On the day of the trials, participants reported to the recreational fields at the University of Arkansas at their allocated time. Each subject read through and signed the IRB-approved consent form, and participants could question the research team. Following consent, each participant submitted 24-hour Western Journal of Emergency Medicine

food and fluid logs, which they were instructed to complete for the day leading up to trials to ensure similar fueling and hydration status between trials. They also affirmed that they had not consumed alcohol within 24 hours or participated in exercise within 12 hours of the study trial. Wet bulb globe temperature was taken every 15 minutes during data collection (Kestrel 4500, Boothwyn, PA). Following consent and paperwork, body mass was measured with a ground scale (Health-o-meter model 349KLX, Buford, GA), height was obtained using a stadiometer, and pretrial urine specific gravity (USG, Master-SUR, Atago Co Ltd, Tokyo, Japan) was obtained to confirm euhydration, which was established as < 1.020. Participants were then instrumented by self-inserting a rectal thermistor (RET-1, Physitemp, NJ) 15 cm past the anal sphincter. To confirm proper instrumentation, a preliminary reading was obtained. If there were invalid readings (< 36 °C or > 38 °C), participants were instructed to further insert the thermistor, or the thermistor was exchanged. Researchers then fit and calibrated participants with a GPS and heart rate (HR) watch (Ironman Triathlon, TIMEX, CT). Both the rectal thermistors and watches were number labeled and matched between trials. Participants were instructed to wear comfortable clothing for exercise and cooling (with potential immersion). Clothing during exercise and cooling was matched for each participant between trials. Participants were considered heat acclimatized due to data collection occurring in September in a midsouthern state. Our exercise protocol was based on previous work demonstrating safe rectal temperature (T-rec) increases in a relatively short time period (18–20 minutes). Participants began their exercise trial with a 400 m self-paced warm-up. Following the 400 m warm-up, they were instructed to complete a 1,609 m run (1 mile) at their own pace around the fields. Following the warm-up, researchers collected (T-rec), HR, and perceptual measures. Perceptual measures included rating of perceived exertion, thirst, and thermal sensation. Participants had 5 minutes to walk around, rest, stretch, and drink water at their discretion. They were also informed that they were not permitted additional fluids for the remainder of the trial. Water consumed was measured in mL following the 5-minute rest and matched between trials. Then, participants began their 50-yard out-and-back sprints for a total of 100 yard sprints. A set was made up of 5 sprints separated by 30 seconds rest between each out-and-back. Once a set of sprints was completed, T-rec, HR, and perceptual measures were recorded during a 3-minute rest period. Participants repeated sets of sprints until either (1) T-rec of 39.2 °C or (2) unwillingness to continue due to exhaustion or signs/ symptoms of heat illness presented. When either of those criteria were met, the 5-minute transition to cooling commenced. Transition included a postexercise body mass measure, which was used to calculate sweat rate during exercise.

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Zashin et al. Cooling was completed in the shade for both conditions, either immersed in a postmortem bag (Cardinal Health Inc, Dublin, OH) with cold water or sitting in the shade. Blinding of participants, researchers and data recorders was not possible during cooling. During the transition, two 10-gallon coolers were filled with one 5-lb bag of ice and water. The body bag was prepped in the grass field under a shaded tent with four seatbelts (Xuesong, China) wrapped around the bag and a half pool-noodle at the participant’s head to keep it propped throughout cooling (Figure 1). Following the 5-minute transition period, perceptual and physiological measurements were taken before cooling began. Body-bag cooling occurred while participants were supine in the bag with 20 gallons of ice water poured on them and the bag zipped and seatbelts closed and cinched around the participant’s body. Four to six researchers surrounded the participant while continuously oscillating the water in the bag. Throughout cooling, T-rec and HR were measured every minute with perceptual measurements taken following treatment. The. CON cooling occurred with the participant lying in the shade on a tarp. The cooling portion of the study was complete when a T-rec of 37.9 °C or 30 minutes of cooling was reached, regardless of trial. After cooling ceased, participants sat upright for 15 minutes to assure recovery from cooling. Following recovery, the trial concluded and investigators removed the monitoring equipment. Participants returned their gear and received hydration and snacks prior to departure. Trials were separated by seven days, and participants who completed both trials were compensated for their time. Sweat rate was calculated according to recommended assessment.21 Data were analyzed using SPSS for Mac (version 24.0; IBM Corp, Armonk, NY). Data for variables with two time points including wet bulb globe temperature, hydration status, and sweat rate were compared using paired samples t-tests. All data for variables with multiple time points were compared using repeated measures analysis of variance. When sphericity was violated, Greenhouse-Geisser corrections were used for interpretation. When a significant time point or interaction existed, post hoc analyses were conducted using Bonferroni correction. Data are presented using mean (SD), and alpha was set a priori as P < .05. RESULTS Two participants did not begin either trial due to outside conflicts preventing participation. One participant suffered a musculoskeletal injury outside data collection following the first trial and could not complete the second trial. Any data gathered from these individuals were not used in the final analysis. Data for 9 participants (8 male; 24 [4] years, 175 [7] cm, 83.6 [21.6] kg); body surface area, 1.99 [.11] m2) were included. Body mass (83.59 [21.61] kg; P = .90) and wet bulb globe temperature (28.43 [1.03] °C; P = .73) were similar between trials. Mile (1,609 m) times between trials (T1: 515.11 Volume 27, Supplement: November 2026

Figure 1. Body bag cooling set-up to treat a participant in a field study to determine whole-body cooling rates when using body bags to treat exertional hyperthermia.

(132.21) seconds vs T2: 491.56 (102.61) seconds) were not significantly different (P = .40). There was no difference in rating of perceived exertion (15.39 [2.72]; P > .99), thirst sensation (6.12 [2.11]; P= .62), or thermal sensation (6.32 [.873]; P = .73) throughout exercise. Physiological measurements of HR (body bag, 183 [14] bpm; CON, 189 [13] bpm; P = .21) and maximum T-rec (body bag, 38.98 [.23] °C; CON, 38.93 [.39] °C; P = .45) showed no significant difference between trials. Cooling rate via body bag was .102 (.04) °C/min whereas CON demonstrated a rate of .04 (.04) °C/min (95% CI, .03.095; P = .002 (Figure 2). Body surface area was not significantly correlated with body bag (r = .20; P = .60) or CON cooling rate (r = –.082; P = .84). Water temperature just prior to pouring into the body bag with participants was 5.2 (1.6) °C. During cooling, thermal sensation was significantly lower with body bag treatment than with CON (P<.001). Total cooling time for CON was 27.6 (4.2) minutes and 13.2 (5.8) minutes with a body bag (95% CI, 9.2-19.5; P = .002). Data for cooling times

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Control

Cooling Time (min)

30 25 20 15 10 5 0 1

Participant

Figure 2. Cooling rate of body bag compared to control in study to determine whole-body cooling rates when using body bags to treat exertional hyperthermia.

Figure 3. Cooling time in a body bag compared to control, based on a crossover study comparing whole-body cooling between partial immersion with body bags and lying in the shade as the control condition.

for each participant between trials are found in Figure 3. DISCUSSION The purpose of this study was to examine the use of partial immersion using a body bag to facilitate whole-body cooling following exertional hyperthermia. Affirming our hypothesis, the body bag method produced faster cooling rates than lying in the shade. Importantly, the body bag produced an “acceptable” (between .078 °C/min and .154 °C/min) cooling rate of .102 (.04) °C/min, making it a viable treatment option that could be included in prehospital care for heat stroke.1-4,11,17 It is important to recognize that a body bag did not achieve ideal cooling rates often associated with cold-water immersion. Emergency medical personnel should continue using whole-body cooling modalities demonstrating 100% survival rate if presented with heat stroke, when feasible.1-4 Body-bag cooling demonstrates successful results due to thermodynamic principles; similar to tarp- assisted cooling with oscillations (TACO).22,23 The key to success for TACO cooling includes immersing the patient in as much cold water as possible and facilitating oscillations. This fosters convective cooling, which accentuates heat transfer from the body. The body-bag method facilitates both principles, making this modality successful in whole-body cooling. Also, water oscillations are typically facilitated during patient transport (driving, turning) to the ED, which suggests that a body bag is an effective prehospital modality. Further, our results are similar to cooling induced using the Polar Life Pod following exertional hyperthermia.19,20 It should be noted that these previous studies used approximately 40 gallons of ice water on the participant to accelerate cooling, which may be a prohibitive amount of water for military and ED settings. Based on thermodynamics, body-bag cooling rates should approximate those documented with the Polar Life Pod given consistent clinical application requiring only 20 gallons of ice water.17 Further, body-bag cooling produces far superior cooling to ice sheet cooling,7,24 which persists in some military Western Journal of Emergency Medicine

settings. Therefore, a body bag represents an effective and more affordable alternative for partial immersion whole-body cooling. Ethically, participants were not allowed to reach the temperature threshold required for heat stroke (> 40.5 °C). Pathophysiology shows that while exertional heat stroke overwhelms the thermoregulatory and cardiovascular systems, they do not shut down.3,8,12 This is similar with exertional hyperthermia, as the thermoregulatory system is overwhelmed but does not fail.3 This principle allows for a study to simulate comparable heat stress to those who suffer heat stroke. Previous data justify extrapolating exertional hyperthermia cooling rates to those expected for exertional heat stroke.5 Previous literature presents similar cooling rates between exertional heat stroke and exertional hyperthermia using the same modality, making it acceptable to infer expected cooling rates for diagnosed heat stroke patients based on data from hyperthermic participants.4,5,17,18 There are clear benefits for the use of a body bag in certain settings compared to cold-water immersion using a large, rigid tub. Body bags can be folded and stored in confined spaces, offering a portable cooling alternative ideal for prehospital and athletic training settings. They are also readily available and accessible in emergency response situations. Further, internet searches on global shopping websites produce a wealth of options. Based on preliminary pilot testing, two 38-L coolers of ice water were poured over participants to maximize immersion depth while minimizing fluid leakage through the zippered seams of the body bags. Body bags for partial immersion could be used in areas of remote endurance events and in military training. These settings could use partial cold-water immersion in a portable and feasible manner to treat hyperthermic patients. Smaller amounts of water may also be effective19 but were not tested in our study. We found it ideal to have approximately five people

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CONCLUSION Research continues to evaluate the outcomes of exertional heart stroke and proper treatment measures. In the ED, during emergency transport, or where cold-water immersion tubs are not readily available, body bags filled with ice water can serve as a medium to adequate cool a heat stroke victim. Based on our data, in settings where full-body immersion is not feasible, partial immersion cooling via a body bag offers an effective alternative for managing hyperthermia. This could be considered for emergency action plans or emergency protocol when heat stroke is an inherent risk.

involved in cooling a single patient with a body bag. One person should remain at the head, keeping the head elevated, with two people on each side of the patient oscillating the water. Other clinician or volunteer numbers could also work as well. It should also be noted that for this cooling medium, an individual needs to be enclosed within the bag and secured with straps, which can be difficult if they are demonstrating central nervous system dysfunction.1 It is crucial that there is proper water immersion and oscillation, and if either cannot be achieved due to symptoms, another more effective cooling modality should be considered. LIMITATIONS There are a few limitations associated with our study. An important limitation was the importance of the thermodynamic principle of convection and its relation to body surface area. Cooling modalities that have a larger body. surface area covered with ice water increase heat transfer and cooling rate.27,28 Given that we standardized the amount of water used in a body bag for each participant, participants with greater body surface area had less depth and partial immersion of ice water. To achieve convection, physical labor was required to move that participant within the body bag. Participants with a larger body surface area required greater physical effort to oscillate due to the increased total mass of the bag. This mechanical limitation may explain the negative correlation observed between body mass and wholebody cooling rates. Studies show that the ratio of fat mass to fat-free mass may limit cooling rate.27 This could warrant research on a specific metric of water immersion necessary to achieve effective cooling rates, rather than a standardized amount of water. We selected an ice water volume that optimizes clinical feasibility across a wide range of athletic, military, and emergency medical settings. An additional limitation was minor body-bag malfunctions. Water leaking from the bags and pooling at the feet likely limited the amount of cold water available for convective and conductive heat transfer. In the future, research should be conducted on a type of body bag and cinching material that produces the least amount of water leakage while maintaining maximal immersion around the thorax. Given our limited sample size of 9 participants who were otherwise healthy, the study may not reflect the effect on actual patients, although cooling rates compared between patients with exertional heart stroke5 and hyperthermic, healthy participants18 typically align. Finally, a clinical limitation of the body bag used in this study is its black coloration, which is typically associated with deceased individuals and could potentially induce psychological distress or patient noncompliance. However, our findings suggest that medical equipment manufacturers could produce structurally identical. Pouches in neutral colors explicitly for hyperthermia management.

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Address for Correspondence: Brendon P. McDermott, PhD, ATC, University of Arkansas, Department of Health, Human Performance and Recreation, 155 Stadium Drive, HPER 306A, Fayetteville, AR 72701. Email: brendonm@uark.edu. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. The authors report no conflicts of interest in the preparation of this study or manuscript. This study was funded only with residual, internal funding mechanisms. No other author has professional or financial relationships with any companies that are relevant to this study. There are no other conflicts of interest or sources of funding to declare. Copyright: © 2026 Zashin et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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13. Stowell JR, Pugsley P, McElhinny M, et al. Emergency management

24. McDermott BP, Anderson SA, Armstrong LE, et al. National Athletic

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Trainers’ Association position statement: fluid replacement for the

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physically active. J Athl Train. 2017;52(9):877-895.

14. Young D, Everitt B, Fine B, et al. Immersive cooling in the prehospital

25. Hosokawa Y, Adams WM, Belal LN, et al. Tarp-assisted cooling as a

setting for heat stroke: a case report. Prehosp Emerg Care.

method of whole-body cooling in hyperthermic individuals. Ann

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15. Jacobsen RC, Beaver B, Abo B. Out-of-hospital cold water immersion

26. Luhring KE, Butts CL, Smith CR, et al. Cooling effectiveness of a

for classic (non-exertional) heat stroke guided by real-time core

modified cold-water immersion method after exercise-induced

temperature monitoring: A case series. Prehosp Emerg Care.

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27. Bongers CCWG, Peggen MAG, Minett GM, et al. Core temperature

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rates in football linemen and cross-country runners with exercise-

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Climate Change: Original Research

Higher Intensity Quality Improvement Campaign Yields Greater Reduction in Medical Glove Use: The “Gloves Off!” Campaign Lai Heng Foong, BMBS, MHS, BA(Hons)*† Matthew Knox, B Adv Sc, MBBS‡ Arunima Malik, PhD, M Teaching, BSc§|| Wendy Hird, BE#

*South Western Sydney Local Health District, Bankstown Lidcombe Hospital, Emergency Department, Bankstown, New South Wales, Australia † University of Sydney, Heat and Health Research Centre, Sydney, New South Wales, Australia ‡ Central Coast Local Health District, Wyong Hospital, Emergency Department, Wyong, New South Wales, Australia § University of Sydney, School of Physics, Integrated Sustainability Analysis, Sydney, New South Wales, Australia || University of Sydney, Business School, School of Accounting, Governance and Regulation, Sydney, New South Wales, Australia # South Western Sydney Local Health District, Sustainability Department, Liverpool, New South Wales, Australia

Section Editor: Gary Gaddis, MD, PhD Submission history: Submitted November 29, 2025; Revision received March 29, 2026; Accepted March 30, 2026 Electronically published September 24, 2026 Full text available through open access at http://escholarship.org/uc/uciem_westjem DOI 10.5811/westjem.56980

Introduction: The healthcare sector contributes 5.4–7.0% of Australia’s total carbon dioxide (CO2) emissions. Among the most ubiquitous items used in healthcare organisations, whether it be hospital, clinic, or community health centres, are gloves. Methods: We reviewed two case studies of the “Gloves Off!” sustainability initiative to compare reduction in glove use and improvement in hand hygiene practice—one that featured a “lowintensity” campaign (Hospital A) and the other a “high-intensity” campaign (Hospital B). Results: A comparison of glove use over the year before and after implementation of the Gloves Off! campaign shows that Hospital A achieved a 2.6% reduction (0.4% reduction per patient), while Hospital B achieved an 11.4% reduction in total glove consumption (7.8% reduction in glove use per patient). Conclusion: Sustainability initiatives can be initiated within busy emergency departments with reduced unnecessary use of nonsterile gloves, decreased CO2 emissions, and cost savings. [West J Emerg Med. 2026;27(6.1)181–185.]

INTRODUCTION The healthcare sector contributes between 5.4–7.0% of Australia’s total carbon dioxide (CO2) emissions.1, 2 Among the most ubiquitous items used in healthcare organisations, whether it be hospital, clinic or community health centres, are nonsterile gloves (NSG). Globally, gloves are used by clinicians for infection control and personal protection. Many reports, including from the World Health Volume 27, Supplement: November 2026

Organization (WHO), have indicated that NSG are being used inappropriately.6 Unnecessary glove use wastes money and increases medical waste, contributing to CO2 emissions from the healthcare sector. In addition, inappropriate glove use has been demonstrated to worsen hand hygiene rates.6 The WHO World Hand Hygiene Day 2025 focused on proper use of disposable gloves during patient care. Annually, the Hunter New England Local Health District 181

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Higher Intensity Quality Improvement Campaign Yields Greater Reduction in Medical Glove Use in New South Wales, Australia, uses 30 million NSG at a cost of 1.5 million Australian dollars (AUD) and an estimated carbon footprint of one million kilograms of CO2 equivalent (kg CO2 eq). The John Hunter Hospital in Newcastle had a Net Zero clinical lead that first launched the Gloves Off! campaign in New South Wales in 2025. Their published study demonstrated3 a reduction after the campaign was initiated. In a study in the United Kingdom, NSG contributed to 45% of the carbon footprint of personal protective equipment used in healthcare.4 An average of 500 million gloves were sent for use in the National Health Service (NHS) and social care per month in 2023, which translates to 16.7 million gloves per day. Studies have shown that the unnecessary use of gloves is as high as 52.9% of care episodes5 to 99% of low-risk procedures.6 The “Gloves Off!” campaign has been launched in multiple hospitals in Australia and globally. Busy clinicians are often neither able nor motivated to embark on a quality improvement (QI) journey due to competing clinical demands and lack of dedicated paid time for QI projects. Objective The objective of this study was to evaluate the effectiveness of a high-intensity versus low-intensity staff awareness and culture-change approach within the Gloves Off! project, specifically in reducing unnecessary glove use in the emergency department (ED). We examined two case studies: one low-intensity and one high-intensity QI program. We focused on two New South Wales Health hospital EDs, one regional and the other urban metropolitan, with different time constraints and resources. Hospital A Hospital A is an urban metropolitan facility in Sydney that sees approximately 60,000 presentations. Hospital B Hospital B is a regional hospital one hour from Sydney that sees 75,000 presentations/year. METHODS Our primary outcome measure was the reduction of glove use in the ED as evaluated by procurement data. We used procurement data for gloves as a surrogate measure of glove use. These data were obtained thorough a standardised database provided by our district sustainability manager. The intervention included education about the proper use of gloves, presentation by an infection control nurse, and clinical champions. We compared two cases: a low-intensity model (Hospital A) and a high-intensity model (Hospital B). Using case studies from these two hospitals in separate local health districts in New South Wales, we assessed the roll out of the Gloves Off! campaign. We selected this approach to determine the workforce, time, and financial resources Western Journal of Emergency Medicine

Foong et al.

required to achieve appropriate glove-use behaviour and quantify the associated cost savings and CO₂ reductions for each model. We compared total glove use over a one-year period before and after the intervention to evaluate the impact of the campaign to reduce glove use. For Hospital A, which commenced the project in October 2024, we defined October 2023–September 2024 as the preintervention period and October 2024–September 2025 as the postintervention period. For Hospital B, which commenced the campaign in February 2024, we defined March 2023–February 2024 as the preintervention period and March 2024–February 2025 as the postintervention period. A full-year timeframe was selected to account for seasonal fluctuations in glove use—recognising that certain months exhibit predictable peaks or troughs—and to ensure a consistent and comparable measure of change across sites. In addition, the evaluation considered two implementation-intensity models: a low-intensity model at Hospital A that featured an education campaign via email and in person; and a high-intensity model at Hospital B characterised by more comprehensive training and intervention activities, complemented by engagement activities. This allowed us to assess how differences in implementation intensity influenced changes in glove use. Hospital A: Low-Intensity Model The ED of Hospital A established a sustainability working group just prior to the launch of the Gloves Off! project in 2024. The members then organised an education campaign to talk about the programme among nurses during usual inservices and doctors during teaching days (only one off). We used a presentation that had been produced by the New South Wales Net Zero Unit in education sessions for nurses and doctors. We included allied health staff and ward orderlies opportunistically. There was no formal launch but rather an announcement in our Microsoft Teams chat and via email. No additional funding was spent for the Gloves Off! campaign beyond coordination and utilising existing education sessions that had already been planned. Emergency department sustainability champions within the working group educated clinical staff about appropriate glove use and displayed reminder posters. Hospital B: High Intensity Model The Gloves Off! programme was implemented in the Hospital B ED using a multifaceted QI approach. Baseline data collection included direct observation of hand hygiene and glove-use behaviours by ED staff, along with analysis of departmental procurement data for nonsterile gloves. These data informed the development of a targeted education intervention. A tailored educational package was delivered through multiple formats, including the following: interactive quizzes during junior medical officer orientation; nursing and clinician

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huddles; in-service sessions; and an on-site launch-day information stall. Additional reinforcement was provided through email communication and the ED newsletter. Supporting signage was installed in key departmental locations, such as glove dispensers and handwashing stations, and near clinical huddle boards. Post-launch evaluation included direct observation of hand hygiene and glove compliance alongside the collection of NSG) procurement data. Campaign implementation at Hospital B cost approximately 600 AUD, which funded launch-day educational snacks for staff and to cover printing costs for department signage. Additionally, staff members volunteered a significant amount of unpaid time to complete the project. RESULTS The results include a pre/postintervention comparison of glove use, both in absolute terms and in the number of gloves used per patient. Hospital A At baseline, glove use was higher at Hospital A. Prior to the Gloves Off! campaign, the Hospital A ED used 1,310,180 gloves annually. Post-campaign, yearly glove use fell to 1,276,750—a reduction of 33,430 gloves (2.6% overall; 0.4% per patient), which is a carbon-equivalent to mitigating 1,136.3 kg CO2 eq. Hospital B Before the Gloves Off! campaign was launched, the ED in Hospital B used 1,030,800 gloves annually. Post-

campaign, glove use fell to 913,400, a reduction of 117,400 gloves (11.4% overall; 7.8% per patient), which equates to approximately 4,000 kg CO2 eq—equivalent to driving 11,000 km in a petrol-powered passenger vehicle. Results of a comparison of glove use over the year before and after implementation of the campaign show that Hospital A achieved a 2.6% reduction in total glove consumption (0.4% reduction in glove use per patient), while Hospital B achieved an 11.4% reduction (7.8% reduction per patient). These findings suggest that both interventions were effective in reducing glove use, with the higher intensity approach implemented at Hospital B appearing to yield a greater impact. The analysis also highlights the potential influence of intervention intensity and implementation strategies on behavioural change in clinical settings. The education campaign was periodically reinforced to ensure that new and rotating staff were reached, including through orientation sessions and short educational videos distributed via the same communication channels. In Hospital B, the project was promoted more broadly within the local health district through the intranet, email updates, sustainability forums, and a leadership forum. External dissemination occurred via the Australasian College for Emergency Medicine Sustainable Emergency Medicine Climate Advocacy Network. The project also received coverage through national media. DISCUSSION Nonsterile gloves are an essential part of a healthcare worker’s equipment to prevent the spread of nosocomial infections and to ensure patient and staff safety. However,

Figure 1. Comparison of glove use in Hospital A (low-intensity model) and Hospital B (high-intensity model), in absolute terms (Panel A) and gloves per presenting patient (Panel B), in a review of the effect of two quality improvement initiatives to reduce unnecessary use of nonsterile gloves in the emergency department

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Foong et al.

resource-stewardship and clinical-care improvement work. The annual cost savings associated with these two QI projects amounted to 1,009 AUD at Hospital A and 4,500 AUD at Hospital B, minus the 600 AUD it cost to implement the projects. The advantage of this project is that no additional expenses were required to conduct these QI projects, while encouraging clinicians to commit to a QI initiative that both saves money and benefits the environment. LIMITATIONS Because both studies were conducted in a region where New South Wales Health has a Net Zero Unit, the results might not be generalizable to other states.

Figure 2. Stages of change model (Prochaska and De Clementi).11

many studies have shown that NSG are used inappropriately in many healthcare settings.7,8 Furthermore, studies have shown that the use of NSG is associated with decreased hand hygiene compliance, increased risk of cross-contamination, and transmission of healthcare-associated infections.9,10 Our results from the two case studies show a difference in the reduction in NSG use between the the two hospitals. Reasons for this difference are multifactorial. Education alone cannot sustain the behavioural change required to maintain this shift in practice. According to the transtheoretical model of change, behaviour change involves many steps and even more to maintain it.11 The stages are precontemplation, contemplation, determination, action, relapse, and maintenance. (See Figure 2) In a busy ED, most staff are focused on delivering patient care. It is difficult to add one more sustainability task in their daily workflow. The action-relapse-maintenance part of the cycle is the most difficult for busy clinicians to maintain. As healthcare professionals, we take an oath to “do no harm.” Unnecessary glove use generates emissions that contribute to climate change, thereby harming patients. We as clinicians have a responsibility to reduce this unnecessary harm. This simple Gloves Off! project allows us to decrease healthcare’s harm on the environment, improve patient care, and fulfill a mandatory job requirement (the QI initiative)—a triple win. For Hospital B, the Gloves Off! project also delivered benefits beyond cost and environmental gains. It is a manageable initiative for busy clinicians that builds practical change-management skills and increases awareness of environmental impacts in the ED. The campaign at Hospital B’s ED catalysed the creation of an active sustainability team that has since delivered multiple high-impact projects and helped establish funded positions with protected time for Western Journal of Emergency Medicine

CONCLUSION Our two case studies using the “Gloves Off!” campaign demonstrate that we can easily introduce a sustainability initiative within busy EDs, with reduced use of unnecessary nonsterile gloves, lower CO2 emissions, and increased cost savings. Our comparison of two different “intensities” of intervention, with differing results, demonstrates that a higher intensity program leads to greater reductions and collateral benefits, including better engagement from clinicians and hospital executives, with improved sustainability for EDs. This scalable initiative could be expanded to other EDs in Australia and around the world.

Address for Correspondence: Lai Heng Foong, BMBS, MHS, BA(Hons), Bankstown Lidcombe Hospital, Department of Emergency Medicine, Eldridge Road, Bankstown 2200 NSW Australia. Email: Lai.foong@health.nsw.gov.au. Conflicts of Interest: By the WestJEM article submission agreement, all authors are required to disclose all affiliations, funding sources and financial or management relationships that could be perceived as potential sources of bias. No author has professional or financial relationships with any companies that are relevant to this study. There are no conflicts of interest or sources of funding to declare. Copyright: © 2026 Foong et al. This is an open access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) License. See: http://creativecommons.org/ licenses/by/4.0/

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