Road Map for K-12 Education - Seven Strategies for Promoting Air Quality

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Road Map for K-12 Education

Seven Strategies for Promoting Air Quality Summer, 2020 V.1.0

Seven Strategies for Promoting Air Quality Since the primary mode of SARS-CoV-2 transmission is person-to-person contact, airborne spread in places where groups congregate is likely because asymptomatic carriers can spread viral particles by talking, sneezing, and/or heavy breathing. Masks can be a first defense but promoting indoor air quality and improving ventilation in school buildings is a key risk mitigation strategy.

Educational Adaptation

Health Promotion

Risk Mitigation


Seven Strategies for Promoting Indoor Air Quality

The concentration of SAR-CoV-2 in indoor air can be reduced by bringing more fresh outdoor air into the building and by filtering re-circulated air to remove airborne viral particles. Use of ultraviolet lights— previously used in healthcare settings to sterilize the air against another infectious airborne disease,

Most Effective

tuberculosis—may help treat COVID-19 in schools.¹

Elimination and Substitution

Hierarchy of Controls, adapted from NIOSH (2015)

Engineering Controls • Air Quality

Administrative Control

Least Effective


Authors / Summer - 2020 Erika Eitland , ScD, MPH Research Analyst 3

Promoting indoor air quality can be challenging for some schools. This may be challenging for some schools, as many buildings may not have reliable mechanical ventilation or operable windows. In June 2020, the U.S. Government Accountability Office released a congressional report stating that more than half of public school districts needed to update or replace multiple systems with an estimated 41 percent of districts needing to update or replace heating, ventilation, and air conditioning (HVAC) in approximately 36,000 schools.²


MERV-16 Filter


Not all mechanical systems may be able to adequately respond or prevent airborne disease transmission and neglected systems may exacerbate the problem. Poorly maintained systems may spread mold spores and allergens that can adversely impact respiratory health. For more information about ventilation in schools also check out the Collaborative for High Performance Schools’ white paper titled School Ventilation for COVID-19.

MERV-8 Test and Commission HVAC systems before school opens

Above: Simple suite of options available to schools, ranked from Most effective at removing airborne transmission risk to least effective


• Open windows • Open classroom doors

Seven Strategies for Promoting Indoor Air Quality

“ Ensure ventilation systems operate properly and increase circulation of outdoor air as much as possible, for example by opening windows and doors. Do not open windows and doors if doing so poses a safety or health risk (e.g., risk of falling, triggering asthma symptoms) to children using the facility.”³ ― CENTERS FOR DISEASE CONTROL AND PREVENTION



01 ― Inspect and assess mechanical systems to ensure they are operating properly to deliver optimal ventilation. If mechanical ventilation is not available, open windows and doors when the weather permits. Bringing more outdoor air into a space can dilute the indoor concentration of airborne virus, as well as help reduce the concentration of volatile organic compounds (VOCs) in the air from enhanced cleaning and disinfection practices.⁴ nj  If windows are not operable: ‒  Open classroom doors to increase circulation, which has the added benefit of not touching the doorknob repeatedly. ‒  Open window blinds to increase UV exposure in classrooms, as UV light from daylighting has been shown to decrease the viability of some infectious disease agents indoors.⁵ Though further research on this tactic is needed for SARS-CoV-2, daylighting is recommended as it’s free and widely available. nj  Be aware that some architectural glass filters out UV light, so this potential benefit is not possible for all buildings. nj  Note: Mechanical heating, ventilation, and air conditioning (HVAC) will have to work harder when windows are open. Communicate with teachers about how to effectively use the systems in their classroom.


Seven Strategies for Promoting Indoor Air Quality

02 ― Increase filtration, when possible. nj  Use portable air filters with High Efficiency Particle Air (HEPA) filtration in smaller shared spaces including restrooms, administrative offices, staff offices. The airflow from portable room air cleaners may be limited and not effective for larger spaces like classrooms, gymnasiums, or cafeterias.⁶ nj  To filter particles, choose a portable air cleaner that has a clean air delivery rate (CADR) that is large enough for the size of the room or area in which you will use it. The higher the CADR, the more particles the air cleaner can filter and the larger the area it can serve.⁷ nj  Work with an HVAC consultant to see if upgrading filtration for your mechanical system is possible with your current system. nj  Minimum Efficiency Reporting Value (MERV) is a rating of a filter’s overall effectiveness. The higher the rating, the more effective the filter is at removing pollutants. MERV-13 filters or higher (compared to the standard MERV-8) are required to capture small viral particles. nj  Recirculated air cannot be made equivalent to fresh outdoor air by removing only particulate contaminants. Noxious, odorous, and toxic contaminants must also be removed by gaseous contaminant removal equipment, which is frequently different from particulate filtration equipment.⁸



03 ― Protect your custodial and facilities budget to increase regular cleaning and maintenance. nj  Clean and change filters in HVAC systems. When filters are removed, maintenance personnel should consider wearing PPE, spraying a sanitizing agent on the filter, and placing the old filter in a sealed plastic bag to allow any active virus to de-activate.⁹ nj  increase floor cleaning and disinfecting since SARS-CoV-2 can be resuspended from the floor and a potential transmission pathway of aerosolized particles.¹⁰ nj  Initiate a preventive maintenance plan over the summer to reduce air quality challenges when schools reopen. The U.S. EPA has preventative maintenance documents as part of their Tools for Schools Program that promote healthy, reliable, and efficient air quality protocols. These tips and tricks can help prevent costly repairs, improve equipment lifetime, and ensure a healthy learning environment¹¹ ‒  This investment makes a difference. “Every dollar spent on preventive maintenance yields $4 in savings by avoiding the costs of future repair or replacement of building systems” ¹²

04 ― Be consistent and have a sustained approach. Indoor air quality is not only important for disease transmission but for general respiratory health. The U.S. EPA’s Tools for Schools resource offers free and low-cost strategies and best practices that schools can implement.¹³ Respiratory health symptoms (e.g. cough, shortness of breath) associated with poor indoor air quality are also common COVID-19 symptoms. Improving air quality can reduce potential stress around false positives and ensure everyone is breathing easier.


Seven Strategies for Promoting Indoor Air Quality

05 ― Humidify, but not too much. Maintaining indoor relative humidity between 40 and 60 percent may help reduce the viability and transmission of SARS-CoV-2 as well as reduce total particulate matter and volatile organic compounds in the air.¹⁴ Moreover, maintaining relative humidity in this range may provide benefits to the respiratory system’s natural defenses against viral infection. nj  For smaller spaces such as administrative offices, portable humidifiers can achieve indoor relative humidity in this range. nj  For across the building, regulate indoor humidity by sealing off cracks (where cold, dry air infiltrates) or by installing a whole-building humidification system that is built into the HVAC system. ‒  DO NOT USE this strategy if your building has evidence of condensation or mold growth. High humidity levels can exacerbate this problem and result in subsequent health concerns.

06 ― Clean and disinfect when occupancy is low and the school is well-ventilated.


Currently designing or building a new school?

Consider displacement ventilation. Studies have shown that this strategy could improve infection control compared to contemporary HVAC systems.  It also results in less acoustic distraction and has fewer diffusers and ductwork.¹⁵

Consider upper room ultraviolet germicidal irradiation (UVGI), which uses low-wavelength ultraviolet light (UVC light) to destroy microorganisms including viruses without the need for high ventilation.¹⁶ This technology could be used to reduce airborne SARS-CoV-2 transmission. Consult with a UVGI expert for more information.


Install real-time sensors to track air quality including temperature, CO2, humidity to allow responsive teacher behavior (e.g. opening windows, increase ventilation). The EPA is involved in the advancement of air sensor technology, including performance evaluations of sensor devices and best practices for effectively using sensors.¹⁷

Seven Strategies for Promoting Indoor Air Quality

― References ¹ 2 Multiple%20Building%20Systems%20Needing%20Updates%20or%20Replacement1.pdf




⁶ 7 home_2nd_edition.pdf





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ouncil of the Great City Schools. 2014. Reversing the Cycle of Deterioration in the Nation’s Public School C Buildings. Washington, D.C.: Council of the Great City Schools. Domain/87/FacilitiesReport2014.pdf.







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