ASHRAE Journal - June 2023 - 34

COLUMN IEQ APPLICATIONS
FIGURE 2 Benefit-to-Cost Ratio24
1000
100
10
Fisk and Chan, 2017
Fisk and Chan, 2017
Zuraimi and Tan, 2015
Montgomery et al., 2015
Beko et al., 2008
1
5
6
7
8
9
10
11
12
13
Minimum Efficiency Reporting Value (MERV)
Benefit-to-cost ratios as a function of MERV for different benefit-cost analysis modeling
investigations. Residential studies are shown with squares; commercial studies are
shown with circles.
for ASHRAE to improve indoor air quality at all
times of building and its HVAC system operation.
The convergence of higher health benefits of small
particle filtration combined with the decreasing costs
of filtering small particles makes this an opportune
time to establish health-based requirements for
controlling PM2.5 in occupied spaces. Perhaps
reducing PM2.5 exposure is as simple as requiring
the equivalent of MERV 13 filtration across the board.
Large central HVAC systems should be fine. But what
FIGURE 3 Pressure Drop24
250
200
150
100
50
418 Pa
MERV 8
MERV 8E
MERV 11E
MERV 14E
433 Pa
1.0
0.8
0.6
0.4
0.2
MERV 8
MERV 8E
MERV 11E
MERV 14E
Pressure drop of different filters placed in different sites sorted by filter type. On each
bar, the lightest color corresponds to the initial pressure drop of a filter, the darker color
represents the midlife (6-week) pressure drop of a filter, and the darkest color shows
the pressure drop of a 3-month filter.
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about the small fan coil unit in a classroom, PTAC in
a nursing home resident room or the mini split in
the local restaurant? The spaces least likely to have
equipment compatible with a thick pleated filter
are often occupied by people most vulnerable to
respiratory harm - children, elderly individuals, sick/
immunocompromised persons and those burdened
with other harmful environmental exposures
correlated with race and class.
Addressing indoor PM2.5 remains a significant opportunity.
ASHRAE is best positioned to create the framework
for reducing indoor environmental exposures
to PM2.5. ASHRAE Standard 62.2 recently increased
minimum MERV requirements from 6 to 11.27 ASHRAE
SSPC 62.1 is currently discussing a change proposal to
require MERV 13 in many spaces. Other ASHRAE committees
involved with standards or guidance should
respond to the evolving understanding of health
impacts of PM2.5.
References
1. Meiklejohn A. 1949. " Pneumoconiosis. " Postgraduate Medical
Journal. BMJ. https://tinyurl.com/3j8bysas
2. Klepis N., W. Nelson, W. Ott, et al. 2001. The National Human
Activity Pattern Survey (NHAPS): a Resource for Assessing
Exposure to Environmental Pollutants. Journal of Exposure
Science & Environmental Epidemiology 11(2001):231-252. https://doi.
org/10.1038/sj.jea.7500165
3. ASHRAE. 2022. " Increased Awareness of Health Impacts of
Indoor PM2.5 and Need for Particulate Matter Control in Occupied
Spaces. " ASHRAE. https://tinyurl.com/55x2k95p
4. WHO. 2023. " Disability-adjusted life years (DALYs). " World
Health Organization. https://tinyurl.com/mv7s2vt5
5. Logue J.M., P.N. Price, M.H. Sherman, et al. 2012. " A Method
to Estimate the Chronic Health Impact of Air Pollutants in U.S.
Residences. " Environmental Health Perspectives 120(2):216-222.
https://ehp.niehs.nih.gov/doi/10.1289/ehp.1104035
6. CDC. 2010. " Aerosol 101. " National Institute for Occupational
Safety and Health. Centers for Disease Control and Prevention.
https://www.cdc.gov/niosh/topics/aerosols/
7. Rockefeller Foundation. 2022. " Getting to and Sustaining the
Next Normal: A Roadmap for Living with COVID. " Rockefeller
Foundation. https://tinyurl.com/7ectbptf
8. Morawska L., J.W. Tang, W. Bahnfleth, et al. 2020. " How can
airborne transmission of COVID-19 be minimized? " Environment
International 142:105832. https://tinyurl.com/24wm3a9f
9. Johnson G.R., L. Morawski, Z.D. Ristovski, et al. 2011.
" Modality of human expired aerosol size distributions. " Journal of
Aerosol Science 12(42):839-851. https://tinyurl.com/mv3ycv48
10. Adenaiye O.O., J. Lai, P.J. Bueno de Mesquita, et al. 2021.
" Infectious Severe Acute Respiratory Syndrome Coronavirus 2
(SARS-CoV-2) in Exhaled Aerosols and Efficacy of Masks During
Early Mild Infection. " Clinical Infectious Diseases 75(1):e241-248.
https://doi.org/10.1093/cid/ciab797
11. Milton D.K., M.P. Fabian, B.J. Cowling, et al. 2013.
Pressure Drop (Pa)
Benefit-to-Cost Ratio
Pressure Drop (IWC)

https://tinyurl.com/3j8bysas https://doi.org/10.1038/sj.jea.7500165 https://doi.org/10.1038/sj.jea.7500165 https://tinyurl.com/55x2k95p https://tinyurl.com/mv7s2vt5 https://ehp.niehs.nih.gov/doi/10.1289/ehp.1104035 https://www.cdc.gov/niosh/topics/aerosols/ https://tinyurl.com/7ectbptf https://tinyurl.com/24wm3a9f https://tinyurl.com/mv3ycv48 https://www.doi.org/10.1093/cid/ciab797 http://ashrae.org

ASHRAE Journal - June 2023

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