Episode 712: Bill Bahnfleth, PhD, PE – ASHRAE Control of Infectious Aerosols Standard & The Future of IAQ Standards..

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Episode 712: Bill Bahnfleth, PhD, PE – ASHRAE Control of Infectious Aerosols Standard & The Future of IAQ Standards..

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Show Resources: Show Discussion:

12:02:59 From cliff zlotnik : Trivia- Name the author of this quotation: "Great works are performed not by strength but by perseverance"?
12:15:58 From Rupal Choksi - Madison IAQ : Will these slides be available?
12:20:35 From Radio Joe : yes
12:45:20 From Kishor Khankari : Indoor airflow patterns and air distribution are another important factors to be considered.
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Re: Episode 712: Bill Bahnfleth, PhD, PE – ASHRAE Control of Infectious Aerosols Standard & The Future of IAQ Standards.

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IAQ RADIO

Show Number: 711 Draft Blog
Bill Bahnfleth, PhD, PE
ASHRAE Control of Infectious Aerosols Standard
&
The Future of IAQ Standards after COVID


Good Day, and welcome to IAQ Radio+ Blog. This week we welcomed back Dr. William Bahnfleth to discuss ASHRAE Standard 241-2023 Control of Infectious Aerosols and the future of IAQ standards after COVID.

William Bahnfleth is a professor of architectural engineering at the Pennsylvania State University. He holds a PhD in mechanical engineering from the University of Illinois and is a Registered Professional Engineer. He is the author or co-author of nearly 200 peer-reviewed publications and 14 books/chapters. He is a past president of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) and was chair of the ASHRAE Epidemic Task Force and currently chairs the project committee for ASHRAE Standard 241 Control of Infectious Aerosols.

Nuggets mined from today’s episode:

Why was the ASHRAE Standard 241 Control of Infectious Aerosols standard started? Because infection transmission occurs primarily indoors only.

Why was the ASHRAE Standard 241 Control of Infectious Aerosols needed? SARS COVID was a good example of the societal disruption caused by an airborne transmitted infection.

Why is the ASHRAE Standard 241 Control of Infectious Aerosols important? While some Healthcare Standards and Codes exist, they don’t address infection transmission indoors. ASHRAE Standard 241 establishes minimum requirements to reduce the risk of airborne aerosol transmission, such as the SARS-COV-2 virus (COVID-19), flu virus, and other pathogens in buildings like homes, offices, schools, and healthcare facilities. Praised by former White House COVID Response Coordinator Dr. Ashish Jha as “…one of the most important public health interventions seen in years,”

What information is in Standard 241? ASHRAE Standard 241 provides comprehensive guidance on designing, installing, commissioning, and maintaining HVAC systems to control the spread of infectious aerosols. The standard also includes recommendations for ventilation rates, filtration and air cleaning technologies, along with a building readiness plan that documents procedures for assessing existing or new HVAC systems to determine if they are working properly.

Z-Man’s Notes from Slides [Slides are attached]
Purpose- establish a standard for controlling infectious aerosols indoors to reduce the risk of diseases.
ASHRAE 241 is NOT an IAQ standard
Risk assessments focused and based upon long transmission (beyond 2 meters) in ambient conditions in spaces where someone is infected with: measles, TB, flu, etc. Pathogen gets into mucus and is distributed as respiratory droplets (submicron-100 microns). 3 Operational Modes: Normal, IRMM (infection risk management mode), & Shutdown.
Definitions
Prerequisites- set minimum requirements for outdoor and filtration
Equivalent Clean Airflow- “the flow rate of pathogen free air distributed uniformly within the breathing zone, would have the same effect on infectious aerosols concentration as the sum of the actual outdoor airflows filtered airflow, and inactivation of infectious aerosols.” Developed a formula:
Vacs=Epr/(100 )×Vrc
ECA requirements are based upon risk assessments and are complex.
Many decisions risk reduction, probabilistic approach, random simulations, Wells-Riley model, risk of infection with confidence levels.
20 different types of spaces
Protective levels- (schools might be 10 ACH, busy restaurant might be 30-40 ACH and consider reducing occupancy)
Air Distribution
Air Cleaners- any technology to remove or deactivate microbes.
Assessment- including building readiness plan documents the plan.
Additional requirements- resilience in IAQ
Appendices
Note: Wildfire smoke also considered- academic taskforce (ASHRAE Guideline 44, mitigation of wildfire smoke). Using 241 will provide wildfire smoke benefits.

Air Cleaners- How do they perform? (e.g. single pass or multi pass through) How well do they perform? How safe are they?
There are standards for UV and filtration. There is an absence of useful test data for ionizers, photocatalytic, hydroxyl generators, etc. Some air cleaners are very effective (e.g. particulate filtration). Others such as UV, photocatalytic, ionizers, etc. are discussed and NOT endorsed due a lack of efficacy and safety testing. Shoe box size test chambers are not the equivalent of large chamber testing (800 F³).
There are safety concerns about some types of air cleaners regarding byproducts and secondary contaminants (e.g. formaldehyde, photolytic particle generation, etc.). Dose response data is needed from negative ion generators, hydroxyls, photocatalytic, UV, etc.
Manufacturers concern’s over testing include: how testing is done, scalability of testing, is the testing is fair and representative.

Is Standard 241 only applicable to new buildings? No, Standard 241 is also applicable to retrofits. IAQ is all about existing buildings!

Regarding airflow patterns and air distribution? ASHRAE 62 says that stratified indoor air patterns are beneficial; 241 says that when it comes to infection control that mixed air patterns are better.

How is Standard 241 being implemented or adopted as a guide for serious disease outbreaks? Standard 241 is the first consensus-based, code enforceable standard of its kind, having the potential for adoption at the federal level for all buildings. It will take an organization willing to lead. So far, 241 has been adopted by: government agencies, well building organizations, and 1 state. Dr Bahnfleth would like to see the federal government recommend the standard. The GSA is interested.

Future of IAQ Dr. Bahnfleth’s final comments:

What other standards are needed?
Standards tell what is expected. Operation and maintenance standards are needed. Need standards for scaling lab results.
Recommendations for Equivalent Clean Air developed for SARS COVID are useful for assessing certain risks during seasonal flu outbreaks, etc. or as a future software tool in which users can input their parameters and get answers.
Would like to see baseline IAQ standards that provide requirements for infection transmission.
Regulations are needed. Municipalities and states adopt earlier than federal government. (Illinois, New Mexico, Massachusetts and NYC. (Johns Hopkins model). Regulation will require the collection and disclosure of data.
Standard 241 is a good start. 241 is less complicated than people think. Game changing ideas for IAQ. Think of 241 as one aspect to address the need to improve IAQ.

Z-Man signing off




Trivia:

Name the author of this quotation: “Great works are performed not by strength but by perseverance.”

Answer: Samuel Johnson

NO CORRECT ANSWER
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Re: Episode 712: Bill Bahnfleth, PhD, PE – ASHRAE Control of Infectious Aerosols Standard & The Future of IAQ Standards.

Post by RadioJoe »

Thanks Bill great job as always. The standard was a big lift and you were the right person to see it through. Cliff's trivia question was apropos.

“Great works are performed not by strength but by perseverance.”
Samuel Johnson
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