Quantifying the health benefits of face masks and respirators to
mitigate exposure to severe air pollution
Abstract
Familiarity with the use of face coverings to reduce the risk of
respiratory disease has increased during the coronavirus pandemic;
however, recommendations for their use outside of the pandemic remains
limited. Here, we develop a modeling framework to quantify the potential
health benefits of wearing a face covering or respirator to mitigate
exposure to severe air pollution. This framework accounts for the wide
range of available face coverings and respirators, fit factors and
efficacy, air pollution characteristics, and exposure-response data. Our
modeling shows that N95 respirators offer robust protection against
different sources of air pollution, reducing exposure by more than a
factor of 14 when worn with a leak rate of 5%. Synthetic-fiber masks
offer less protection with a strong dependence on aerosol size
distribution (protection factors ranging from 4.4 to 2.2.), while
natural-fiber and surgical masks offer reductions in exposure of 1.9 and
1.7, respectively. To assess the ability of face coverings to provide
population-level health benefits to wildfire smoke, we perform a case
study for the 2012 Washington state fire season. Our models suggest that
although natural-fiber masks offer minor reductions in respiratory
hospitalizations attributable to smoke (2-11%) due to limited
filtration efficiency, N95 respirators and to a lesser extent surgical
and synthetic-fiber masks may lead to notable reductions in
smoke-attributable hospitalizations (22-39%, 9-24%, and 7-18%,
respectively). The filtration efficiency, bypass rate, compliance rate
(fraction of time and population wearing the device) are the key factors
governing exposure reduction potential and health benefits during severe
air pollution events.