Expiratory aerosol particle escape from surgical masks due to imperfect sealing

Abstract Wearing surgical masks or other similar face coverings can reduce the emission of expiratory particles produced via breathing, talking, coughing, or sneezing. Although it is well established that some fraction of the expiratory airflow leaks around the edges of the mask, it is unclear how t...

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Autores principales:	Christopher D. Cappa, Sima Asadi, Santiago Barreda, Anthony S. Wexler, Nicole M. Bouvier, William D. Ristenpart
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/1d25ca27afd446afa5f08293dba02b00
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spelling	oai:doaj.org-article:1d25ca27afd446afa5f08293dba02b002021-12-02T17:34:35ZExpiratory aerosol particle escape from surgical masks due to imperfect sealing10.1038/s41598-021-91487-72045-2322https://doaj.org/article/1d25ca27afd446afa5f08293dba02b002021-06-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-91487-7https://doaj.org/toc/2045-2322Abstract Wearing surgical masks or other similar face coverings can reduce the emission of expiratory particles produced via breathing, talking, coughing, or sneezing. Although it is well established that some fraction of the expiratory airflow leaks around the edges of the mask, it is unclear how these leakage airflows affect the overall efficiency with which masks block emission of expiratory aerosol particles. Here, we show experimentally that the aerosol particle concentrations in the leakage airflows around a surgical mask are reduced compared to no mask wearing, with the magnitude of reduction dependent on the direction of escape (out the top, the sides, or the bottom). Because the actual leakage flowrate in each direction is difficult to measure, we use a Monte Carlo approach to estimate flow-corrected particle emission rates for particles having diameters in the range 0.5–20 μm. in all orientations. From these, we derive a flow-weighted overall number-based particle removal efficiency for the mask. The overall mask efficiency, accounting both for air that passes through the mask and for leakage flows, is reduced compared to the through-mask filtration efficiency, from 93 to 70% for talking, but from only 94–90% for coughing. These results demonstrate that leakage flows due to imperfect sealing do decrease mask efficiencies for reducing emission of expiratory particles, but even with such leakage surgical masks provide substantial control.Christopher D. CappaSima AsadiSantiago BarredaAnthony S. WexlerNicole M. BouvierWilliam D. RistenpartNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-12 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Christopher D. Cappa Sima Asadi Santiago Barreda Anthony S. Wexler Nicole M. Bouvier William D. Ristenpart Expiratory aerosol particle escape from surgical masks due to imperfect sealing
description	Abstract Wearing surgical masks or other similar face coverings can reduce the emission of expiratory particles produced via breathing, talking, coughing, or sneezing. Although it is well established that some fraction of the expiratory airflow leaks around the edges of the mask, it is unclear how these leakage airflows affect the overall efficiency with which masks block emission of expiratory aerosol particles. Here, we show experimentally that the aerosol particle concentrations in the leakage airflows around a surgical mask are reduced compared to no mask wearing, with the magnitude of reduction dependent on the direction of escape (out the top, the sides, or the bottom). Because the actual leakage flowrate in each direction is difficult to measure, we use a Monte Carlo approach to estimate flow-corrected particle emission rates for particles having diameters in the range 0.5–20 μm. in all orientations. From these, we derive a flow-weighted overall number-based particle removal efficiency for the mask. The overall mask efficiency, accounting both for air that passes through the mask and for leakage flows, is reduced compared to the through-mask filtration efficiency, from 93 to 70% for talking, but from only 94–90% for coughing. These results demonstrate that leakage flows due to imperfect sealing do decrease mask efficiencies for reducing emission of expiratory particles, but even with such leakage surgical masks provide substantial control.
format	article
author	Christopher D. Cappa Sima Asadi Santiago Barreda Anthony S. Wexler Nicole M. Bouvier William D. Ristenpart
author_facet	Christopher D. Cappa Sima Asadi Santiago Barreda Anthony S. Wexler Nicole M. Bouvier William D. Ristenpart
author_sort	Christopher D. Cappa
title	Expiratory aerosol particle escape from surgical masks due to imperfect sealing
title_short	Expiratory aerosol particle escape from surgical masks due to imperfect sealing
title_full	Expiratory aerosol particle escape from surgical masks due to imperfect sealing
title_fullStr	Expiratory aerosol particle escape from surgical masks due to imperfect sealing
title_full_unstemmed	Expiratory aerosol particle escape from surgical masks due to imperfect sealing
title_sort	expiratory aerosol particle escape from surgical masks due to imperfect sealing
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/1d25ca27afd446afa5f08293dba02b00
work_keys_str_mv	AT christopherdcappa expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing AT simaasadi expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing AT santiagobarreda expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing AT anthonyswexler expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing AT nicolembouvier expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing AT williamdristenpart expiratoryaerosolparticleescapefromsurgicalmasksduetoimperfectsealing
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Expiratory aerosol particle escape from surgical masks due to imperfect sealing

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