The Path to Finalizing New Standard for Infectious Aerosols

On May 15th, ASHRAE notified the market and public that a draft of a proposed standard for control of infectious aerosols, ASHRAE 241P, was available for review and comment. This proposed standard is the output of work previously announced December 9, 2022, “ASHRAE’s board of directors today announced its commitment to support the expedited development of a national indoor air quality (IAQ) pathogen mitigation standard. The goal is to finalize the consensus-based, code enforceable standard within six months.” Consistent with efforts to expedite the development and implementation of this standard, the commenting period was limited in duration and closed on May 26th.

ASHRAE voted to approve the final draft of the standard on June 30, and it was applauded by former White House COVID-19 Response Coordinator Dr. Ashish Jha. “This effort to try to improve indoor air quality and reduce the burden of respiratory pathogens is something we have talked about at the White House – a lot of experts have been talking about it,” said Dr. Jha. “Talking is important, but what ASHRAE did over the last six months in building out Standard 241, that just got approved, fundamentally changes the game. It is one of the most important public health interventions I have seen in years, if not decades. It is really heartening to see this organization take a central role in tackling the biggest challenges facing human health in the U.S. and around the world.” effects on fair competition,” “not stifle innovation and technological development,” and that “standards are instrumental in helping to more rapidly allow multiple companies to compete at various points throughout supply chains, thereby reducing cost, improving competitiveness, and enabling continuous innovation.” To ensure efficient validation that products adhere to standards and to promote innovation, test methods in standards should “offer definitive precision, accuracy and reliability (PAR) statements. The (PAR) is based on Precision & Bias (P&B) data achieved through an Inter-Laboratory Study (ILS). An ILS is a mandatory aspect of all ASTM standards that demonstrates how effectively different operators, laboratories and test instruments implement the method, which ultimately defines the precision, accuracy and reliability.”

INDA, in its role representing the nonwovens and engineered materials industry, collected input from manufacturers of filter media and provided the statement below.

To Whom It May Concern:

Our organization, INDA – The Association of the Nonwovens Fabric Industry, has reviewed the proposed ASHRAE Standard 241P “Control of Infectious Aerosols” and would like to provide the following comments for consideration before adoption. As an organization comprised of companies that provide the physical filter media, we will limit our comments to those relevant to those materials.

As director of education and technical affairs, Matt presents regular training related to nonwovens and filter media from INDA’s headquarters in Cary, NC.

For more information about upcoming training opportunities, visit inda.org/training

Standard 241 establishes minimum requirements for controlling infectious aerosols and reducing the risk of disease transmission in new and existing buildings. Included are requirements for both outdoor air system and air cleaning system design, installation, commissioning, operation, and maintenance to reduce exposure to infectious aerosols.

Advising for Common Sense

INDA – The Association of the Nonwovens Fabric Industry’s philosophy for new standards and test methods reflects that of WTO and standard development organizations such as ANSI, ASTM, TAPPI and ISO, in that standards should: “Effectively respond to regulatory and market needs,” “be performance based as opposed to design prescriptive,” “have no adverse

Founded in 1968, INDA member companies represent the entire nonwovens value chain including raw materials and roll goods producers, machinery manufacturers, converters, and brand owners. INDA works each day to fulfill our mission of “fostering member and industry success through its activities.” INDA provides thought-leadership in innovation and technology through conference content, recognition awards, and industry reports; protecting markets that are important to our members through focused product stewardship; advocating for industry sectors impacted by regulatory or consumer-driven issues; and organizing face-to-face interaction through industry expositions and events.

Direct nonwoven manufacturing is a nearly $20 billion industry in North America with tens of bil- lions more in indirect economic impact and sales to end users. INDA members include the manufacturers of thousands of durable and disposable products such as personal care items, hygiene products, PPE, medical equipment, construction materials, automotive fixtures, and filtration media.

As a general tenet, INDA strongly supports standards that are based upon scientific evidence that has been peer reviewed and is not prescriptive with respect to future product innovation. The rich history of innovation in filter media has provided multiple options for meeting MERV 13 and higher air filtrations requirements.

We recognize that proposed Standard 241P is specifically targeting control of infectious aerosols and is not meant to displace other indoor air quality standards. With this in mind, as the CDC has provided the scientifically supported guidance that MERV 13 is the minimum requirement to achieve the desired control of infectious aerosols, we recommend that only MERV 13 and higher filters be addressed by this standard. This provides consistency between guidance from national health agencies and the proposed standard.

As noted above, innovations in filter media, both with and without electrostatically charging, have provided a number of options to achieve the performance requirements described in Standard 241P. The proposed standard attempts to ensure that filter media meet minimum filtration requirements throughout its designed useful life and includes a discharge conditioning step to comply with the MERV-A performance beyond January 1, 2025. The following comments regarding the discharge conditioning pertain only to those filter media that are electrostatically charged to boost performance. Other compliant media available today, that do not use electrostatic charging, should be unaffected by this requirement.

In so far that Standard 241P references ANSI/ASHRAE Standard 52.2 (section 4.2.3) and in 2025 will make mandatory a conditioning step, as provided in Appendix J of Standard 52.2, we believe recent actions related to that standard should be considered. In February 2023, when proposed to make this conditioning step mandatory rather than optional, the proposal failed passage and it was recommended that a study be done to obtain scientific understanding of the efficiency loss in electrostatically charged filters. As Standard 241P is linked to Standard 52.2 by reference, we believe that the scientific study recommended by the committee for Standard 52.2 be completed to ensure that the discharge conditioning method is meeting the intent of Standard 241P and appropriately reflecting the performance of filter media.

As the test methodology required for the MERV-A filter media conditioning step, it is noted to have appreciable variability and lab-to-lab variance. We encourage ASHRAE to address these concerns while completing the study recommended by the ASHRAE 52.2 Standards Committee pertaining to Appendix J. To alleviate the concerns pertaining to lab-to-lab variation, it is recommended that labs evaluating filter media have third-party certification for the appropriate methods.

The filter conditioning step required for MERV-A, provides the additional data point of “worse case” performance for electrostatically charged filters, which, considering the goal of infectious aerosol control, has some value. Coupled with the best case/fresh out of the package MERV rating, the breadth of filter capability is potentially identified. While an improvement over a single data point, this still neglects the performance during the majority of the product life. ISO 16890 recognizes this shortcoming and attempts to address this via an average of “as is” and “conditioned” filter performance. Of course, for media that is not electrostatically charged to boost performance, these values should be essentially the same. A final note here – the mention of ISO 16890 was not to suggest that ASHRAE Standard 241P should follow the ISO approach. While there is value to standard harmonization, that effort is out-of-scope here.

One key indoor air quality learning from the COVID-19 pandemic is that filter media has often not been changed with appropriate frequency resulting in higher operational energy costs, increased maintenance costs, reduced equipment operational lifespan, and most importantly lower-performing air filtration and control of infectious aerosols. In many instances, it has been noted that the failure to replace filter media was due to the cost of the media itself. With the goal of controlling infectious aerosols, consistently over time, there is a need to be sensitive to the total implemented costs, including media and operating costs.

Considering this, it is anticipated that there will be increases in both the time and cost of testing filter media using the methods required for MERV-A, as provided by ANSI/ASHRAE Standard 52.2 Appendix J. These costs will of course be incorporated into the cost of the filter media, potentially exacerbating the issues with timely filter replacement. Thus, it is of high importance that there is confidence in the test methodologies to avoid excessive testing and/or re-testing and that the methods are adequately reflecting filter media use behavior.

Lastly, it should be noted, that by requiring MERV-A 13 performance there will be many instances of filter media operating with higher pressure drop which will translate into higher operational energy costs. Eventually, this will drive innovation to achieve the desired levels of infectious aerosol filtration in a more cost-friendly operational manner, but many short-term solutions will have a higher energy and/or carbon footprint. Long-term innovative solutions may contain combinations of technical approaches, both old and new, to achieve the combined performance and economic aspects to ensure improved infectious aerosol control.

By Len LaPorta Managing Director, Wiley Bros.-Aintree Capital, LLC

Len LaPorta is a managing director of Investment Banking at Wiley Bros.-Aintree Capital, LLC – a 75-year-old firm, located in Nashville, TN, focused on investment brokerage and underwriting municipal bonds for utility districts in the state of Tennessee. Len brings to the Firm experience in crossborder M&A transactions between USA and Europe, advises business owners on sell-side and buy-side transactions, capital advisory, and valuations. Len is a graduate of the U.S. Naval Academy with MBA from Boston College and a veteran of the U.S. Navy. He is also a member of INDA’s non-woven Technical Advisory Board. llaporta@wileybros.com or (615) 782-4107.