by Keith Jordan, MBA, President, Colorado Air Filter LLC
I have been in the Indoor Air Quality industry for the past 15 years and have experienced other pandemics such as Bird Flu, Swine Flu, MERS, SARS, Ebola, and the Zika virus and one common theme occurred after each pandemic slowed and passed – people forgot about air quality! People went back to their daily routines, stopped protecting themselves, stopped worrying about a potential deadly disease, stopped equipping their facilities to protect occupants, stopped maintaining Indoor Air Quality equipment they installed to help with a pandemic.
Repeating the pattern?
We are now coming out of a 100-year Global Pandemic of SARS-CoV 2 and I am afraid we are seeing the same pattern begin to happen. While many schools and universities continue to equip their AHU and RTU with MERV 13 filters, many commercial office buildings, religious buildings, and manufacturing facilities have gone back to MERV 8 and are not actively promoting a higher level of Indoor Air Quality. While I recognize there is a vaccine for COVID 19 which will cause many to relax, the threat of a new pandemic looms on the horizon. Pandemics occur approximately every 5-9 years and if we fail to stay vigilant and prepared, we will not be ready for the next one.
Micro-organisms have been on the earth for hundreds of millions, potentially billions of years. Humans can’t beat them; we must learn to live with them and proactively protect ourselves from them. Outside of vaccines, let’s discuss what facilities can do to protect their employees, occupants, patients, or customers from airborne infectious aerosols and be better prepared for the next pandemic.
For the last few decades, we designed our buildings to save energy and protect the HVAC equipment. In many cases protecting the equipment doesn’t necessarily protect the occupants. As air filtration and attention to Indoor Air Quality has heightened, we are starting to implement Indoor Air Quality measures that will protect both the occupants and in turn, the equipment. Humans are our most precious resource and building owners, designers, and maintenance personnel should change their perspective on Indoor Air Quality and understand how important it is for the health, safety, and productivity of tomorrow’s buildings. We as Air Filtration and Air Quality professionals should continue to push for higher standards, push for higher education and hold our customers accountable for their air quality. Given our technological advancements in filtration, air cleaning and air disinfection, there is no excuse to not implement permanent improved measures moving forward.
In the latest edition of ASHRAE Journal Dec 2022, an article titled “Developing Indoor Air Quality Standards: Reflecting on a White House Summit” (see page 8) outlines how IAQ experts are rapidly working on implementing lessons learned from the COVID pandemic. This time could be different, the IAQ experts will not allow the public to forget.
In the first sentence, the White House Coronavirus Response coordinator emphasizes that there are two choices – prevention or repair. Essentially, America can help prevent people from getting sick or spend extra money trying to deal with a larger sick population. We all agree that prevention is a much better solution, but implementing it is a different problem. It comes down to funding, education, and implementation. I can’t help with the funding portion of the problem, but I can help with education and implementation. Let’s discuss in more detail how ASHRAE recommends facilities to prepare for the next pandemic.
- The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) tasked former ASHRAE President William Bahnfleth, PhD with the goal of putting together a task force to study and recommend guidelines for Infectious Aerosol mitigation during the start of the COVID pandemic. Dr. Bahnfleth has formed a team of top professionals in the Heating, Ventilation and Air Conditioning (HVAC) Industry and with combined knowledge of the history of pandemics such as SARS, MERS, Bird flu, swine flu, and Zika, the task force knew very quickly that this novel coronavirus, SARS CoV 2 would be spread via airborne aerosols. Thus, the Epidemic Task Force recommends five core strategies to help limit the spread of airborne infectious aerosols within a building.
- Upgrade filtration to MERV 13 or better where possible
- Commissioning – building tune-up
- Increase ventilation when possible
- Control humidity
- Utilize UVGI or portable air cleaner
Let’s briefly cover each recommendation to help NAFA members provide more detail and education to Facility Managers, Chief Engineers, Maintenance Technicians and Mechanical Engineers.
Upgrade filtration to MERV 13 or better where possible
ASHRAE Standard 62.1 generally requires filters in HVAC systems of at least MERV 8. As you can see in the chart below, a MERV 8 filter has no performance benefit on a particle or aerosol in the 0.3-1.0 um size.
|Particle Size||MERV 8||MERV 13|
|E3 – 3 – 10 um||70%||90%|
|E2 – 1 – 3 um||20%||85%|
|E1 – .3 – 1 um||0%||50%|
Additionally, there is an exponential difference in performance between a MERV 8 and a MERV 13 filter within the E2 aerosol and particle range. SARS CoV 2 is transmitted via aerosols as we talk, breathe, cough or sing. These aerosols range from 10 to smaller than 1 um with the target aerosol being in the E2 – 1-3 um range. These aerosols or particulate could enter deep into our lungs causing respiratory issues. Many IAQ experts are pushing for the standard to be raised from MERV 8 to MERV 13. As more data and research into E2 size range particles are performed, expect the conversations to increase concerning the greater implementation of MERV 13 filters. Now, this recommendation is not without one caveat. In some cases, the filters’ air resistance or how much force it takes to push or pull air through the filter is too great for the HVAC unit’s fan or compressor due to several factors such as age of unit, type of motor or type of filter rack. There are a few ways to overcome those obstacles such as switching to a new filter rack accommodating a 2” or 4” filter to help lower the pressure drop. Secondly, utilize multiple stages of filtration or add additional air cleaning products such as UVGI in the air handler to aid in the disinfection of mold, virus, and bacteria. Lastly, upgrading the fan motor to handle more static pressure could be another great solution. For more information refer to the ASHRAE position document on Filtration and Air Cleaning 2015 and ASHRAE Position Document on Indoor Air Quality 2021.
Commissioning – building tune up
A recent study of the U.S. Government Accountability Office report found that more than 40% of school districts required replacement or upgrade of their HVAC systems. (U.S. Government Accountability Office. 2020. “K-12 Education: School Districts Frequently Identified Multiple Building Systems Needing Update or Replacement.” https://www.gao.gov/products/gao-20-494) Many older facilities will have an inadequate fan, condenser motors or duct dimensions to utilize a MERV 13 filter.
These facilities are highly recommended to upgrade their systems where possible and utilize the ASHRAE retro-commissioning process to achieve the desired performance. More information can be found in the ASHRAE 2008 document Indoor Air Quality Guide: Best Practices for Design, Construction, and Commissioning.
Increase ventilation where possible
The third core recommendation for infectious aerosol control is to increase the percentage of ventilation within the building. Increased ventilation rates can be achieved by introducing more outside air, by recirculating air through a MERV 13 filter or utilizing other treated air. Some climates are better suited for increased outside air; however, buildings must be mindful of their energy usage and choose the best ventilation method as dictated by their climate and humidity. In many studies, treated outdoor air ventilation rates have shown a positive correlation with indoor air quality, including reduced sick building syndrome symptom, reduced absenteeism, better task performance and increased learning performance (Sundell et. Al. 2011) Likewise, higher ventilation rates are associated with lower incidence of airborne diseases. For additional details on recommended ventilation measures, see the ASHRAE position on Infectious Aerosols: October 13, 2022.
The fourth core recommendation would be to control humidity within a building, with an objective of maintaining a 40% – 60% humidity level. Research indicates that maintaining the relative humidity between 40% – 60% decreases the infectivity and reduces the viability of many airborne infectious aerosols. In addition, peak comfort for the occupants can also be achieved within this recommended humidity range. As with the other recommendations, if humidity cannot be maintained between 40% – 60%, then other mitigating measures should first be implemented.
Utilize UVGI or a portable air cleaner
The fifth core recommendation is to utilize an Ultraviolet Germicidal Irradiation system (UVGI) in the HVAC unit or a portable air cleaner. Ultraviolet Germicidal irradiation (UVGI) has been utilized for over 100 years in both the water and air disinfection industries and has been proven to disinfect mold, virus and bacteria both in the airstream and on a surface when sized correctly. UVGI is a top recommendation when dealing with any airborne or surface borne micro-organisms. It will reduce the bioburden without any increase in pressure drop. A building can also use a portable air cleaner such as the Rosenthal-Corsi box or a commercially available air cleaner utilizing a HEPA filter. Portable air cleaners can be placed anywhere inside a room and can provide additional air cleaning to the forced air system or replacement air cleaning if no forced air system is being utilized. Higher numbers of air changes per hour will perform better over time across all particle sizes than simply looking for a unit with a HEPA filter and a low-speed fan. Additionally, the status of air cleaning technologies is reviewed in the ASHRAE Position Document on Filtration and Air Cleaning (ASHRAE 2021).
While there are additional methods to help slow the impact of infectious aerosols, we’ve only covered the core recommendations by the ASHRAE Epidemic task force. Please utilize these as beginning discussions with your customers. These are not hard and fast rules and if you’ve been in the filtration industry for any length of time, you know there are always exceptions. Let’s instead focus on education and helping prepare your customers for the next pandemic. It is our responsibility as air quality professionals to prepare, preach and help position our current and future generations actions to diminish the next airborne pandemic.
- The White House. October 12, 2022. White House Summit on Indoor Air Quality. https://youtube/q1HCG1aXaBg
- Burley, Ph.D., P.E., Brendon. 2022 “Developing Indoor Air Quality Standards: Reflecting on a White House Summit.” ASHRAE Journal 64:.
- ASHRAE Epidemic Task Force. 2021. “Core Recommendations for Reducing Airborne Infectious Aerosol Exposure.” https://ww.ashrae.org/file library/technical resources/ covid-19/core-recommendations-for-reducing-airborne-infectious-aerosol-exposure.pdf
- ANSI/ASHRAE/ASHE Standard 62.1-2002. Ventilation and Acceptable Indoor Air Quality.
- Allen J.G., A.M. Ibrahim. 2021. Indoor Air Changes and Potential Implications for SARS-CoV-2 Transmission. JAMA 2021 25.325(20):2112-2113. Doi: 10.1001/jama.2021.5053
- ASHRAE., 2008. “Indoor Air Quality Guide: Best Practices for Design, Construction, and Commissioning.” https://iaq.ashrae.org/
- ASHRAE.2019a. Chapter 62, “Ultraviolet Air and Surface Treatment.” In ASHRAE Handbook – 2019 HVAC Applications. Peachtree Corners, GA: ASHRAE
- ASHRAE. 2021. ASHRAE Position Document on Filtration and Air Cleaning. Peachtree Corners, GA: ASHRAE.
- ASHRAE Position Document on Indoor Air Quality. 2020. ASHRAE., https://www.ashrae.org/file library/about/positions documents/pd_indoor-air-quality-2020-07-01.pdf
- ASHRAE. Positions on Infectious Aerosols. ASHRAE., 2022. https://www.ashrae.org/File%20Library/About/Position%20Documents/PD_-Infectious-Aerosols-2022.pdf
- Sundell, J., H. Levin, W.W. Nazaroff, W.S. Cain, W. J. Fisk, D.T. Grimsrud, F. Gyntelberg, Y. Li, A.K. Persily, A.C. Pickering, J.M. Samet, J.D. Spengler, S.T. Taylor, and C. J. Weschler, 2011. Ventilation rates and health: Multidisciplinary review of the scientific literature. Indoor Air 21(3):191-204. https://doi.org/10.1111/j.1600-0668.2010.00703.x.
- Jones, E.R., M.V. Rainbold, L.C. Marr. D. Michaels, et al. 2022. The First Four healthy Building Strategies Every Building Should Pursue to Reduce Risk from COVID-19. Lancet COVID-19 Commission Task Force on Safe School, Safe Work, Safe Travel. https://covid19commission.org/safe-work-travel.
- Wyon. D.P., P. Wargocki. 2013. “How indoor environment affects performance.” ASHRAE Journal 55.46-53
- World Health Organization. 2021. WHO Global Air Quality Guidelines. Particulate matter (PM2.5 and PM10), ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. WHO. Geneva. Switzerland.