TITLE:
Practical Mitigation Strategies for Countering the Spread of Aerosolized COVID-19 Virus (SARS-CoV-2) Using Ventilation and HEPA Air Purifiers: A Literature Review
AUTHORS:
Panayiotis Polyzois, Shirley Thompson
KEYWORDS:
COVID-19, SAS-CoV-2, Aerosolized, Ventilation, HEPA Air Purifier(s)
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.9 No.9,
September
29,
2021
ABSTRACT: This paper assesses, through an extensive
literature review, the use of ventilation and High-Efficiency Particulate Air
(HEPA) purifiers as practical mitigation strategies for reducing the spread of
aerosolized COVID-191 virus. HEPA is a well-defined standard by the U.S.
Department of Energy for filters. The focus of the literature review was on
indoor air quality (IAQ) and COVID-19, with a particular emphasis on classroom
settings. The start of the review, January 2020, was chosen to coincide with
the first cases of COVID-19 in North America. Although children under the age
of 12 are currently not yet vaccinated, there is mounting pressure for a return
to normal by the start of the new school year, 2021. Also, many classrooms lack
pre-installed mechanical ventilation systems (Olsiewski et al., 2021);
therefore, mitigation in classrooms often falls solely in the hands of teachers
and students. Research shows that ventilation and air purification are
essential tools to counter aerosolized transmission (Curtius et al. (2020), the inhaled dose of particles
containing virus RNA is six times lower when using air purifiers with an ACH
(air changes per hour) of 5.7. However, ventilation and air purifiers are not
replacements for masks, which remain vital for countering droplet (>5 μm)
transmission. In addition, occupancy (i.e., number and proximity of people
present in a given area) and group activity levels (e.g., talking, shouting,
singing) play a critical role in viral transmission. Although natural
ventilation by opening windows can be an essential strategy to help counter the
spread of the virus, the level of ventilation offered by opening windows is
largely uncontrollable as it is subject to weather conditions and building design. One must
also consider the energy implications (i.e., loss of heat) that this strategy
carries. Scientific evidence shows that varying levels of continuous and/or
intermittent ventilation, either mechanical or natural, combined with the use of
HEPA air purifiers, can provide a higher degree of protection than window
access alone (Curtius et al., 2020). Systematic deployment of a hybrid
mitigation strategy incorporating both ventilation and HEPA air purification in
schools, offices, or other facilities offers a practical way to establish a
safe re-opening of society in Canada.