ASHRAE Journal - May 2020 - 74

COLUMN IEQ APPLICATIONS

of Viruses) to the disease caused by SARS-CoV-2, aka the novel
coronavirus. Hospitals and health-care facilities are beyond the scope
of this article, though many of the same principles apply to them.
2. "NIH Director: 'We're on an Exponential Curve'", The Atlantic,
Peter Wehner, March 17, 2020.
3. Bischoff 2013. References cited with only a name and date
in this article are taken from ASHRAE Position Document on Airborne
Infectious Diseases, 2014, 2020 ("PD"). According to the PD, there is no
exact size demarcation between droplets and particles, and this "... is
less important than knowing that large droplets and small particles

behave differently and that the latter can remain airborne."
4. Yu et al. 2004; Li et al. 2005a, 2005b. References from ASHRAE
Position Document on Airborne Infectious Diseases.
5. "Aerodynamic Characteristics and RNA Concentration of SARSCoV-2 Aerosol in Wuhan Hospitals during COVID-19 Outbreak," nonpeer reviewed preprint. bioRxiv, posted March 10, 2020.
6. "Aerosol and Surface Stability of SARS-CoV-2 as Compared
with SARS-CoV-1," letter to the editor New England Journal of Medicine,
March 17, 2020, DOI: 10.1056/NEJMc2004973.
7. Non-health care workplaces fall into the medium and lower
exposure risk categories described in
Guidance on Preparing Workplaces for COVID-19,
U.S. Department of Labor, Occupational
Safety and Health Administration OSHA
3990-03 2020.
8. Stay at home orders have been
incorrectly called "shelter in place." The
latter is a more extreme action advised
when there is an outdoor contaminant,
which is not the COVID-19 situation. See
https://emergency.cdc.gov/planning/
shelteringfacts.asp.
9. To paraphrase the words of the singersongwriter Joe Jencks, janitors, cleaners,
nurses, aides, doctors, EMTs and other ﬁrst
responders are our "viral ﬁreﬁghters," the
advance guard in the ﬁght against this virus.
10. This applies to systems that deliver
air to the occupied space and, to a lesser
extent, room air returned to rotary heat
exchangers, in order to reduce cross
contamination.
11. MERV-13 is approximately equivalent
to F7, a rating used in the EU. More effective
ﬁlters with reasonable pressure drop are
available, and some increased pressure
drop often results in an acceptably small
effect on system performance.
12. Consider the ﬁlters contaminated,
protect personnel changing them, and seal
them in plastic bags for disposal.
13. There is research that shows UVGI
in both the upper-room and in-duct
conﬁgurations can inactivate some
disease-transmitting organisms. Either
of these takes time to plan and install. For
more information, see the ASHRAE PD
previously cited and Chapter 62 Ultraviolet
Air and Surface Treatment of 2019 ASHRAE
Handbook-HVAC Applications.
14. N95 masks are in short supply and
some contractors are donating them to
medical facilities, according to Engineering
News Record March 18, 2020 "Construction
Firms Respond to Mask Donation Need."
15. Engineering News Record, March 19,
2020. "Pennsylvania Halts All 'Non-LifeSustaining Business" Operations, Including
Construction."

A version of this column ﬁrst appeared
in ASHRAE Journal
Newsletter.
74

ASHRAE JOURNAL

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M AY 2020

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ASHRAE Journal - May 2020

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