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Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities

The COVID-19 pandemic triggered a surge in demand for facemasks to protect against disease transmission. In response to shortages, many public health authorities have recommended homemade masks as acceptable alternatives to surgical masks and N95 respirators. Although mask wearing is intended, in pa...

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Autores principales: Asadi, Sima, Cappa, Christopher D., Barreda, Santiago, Wexler, Anthony S., Bouvier, Nicole M., Ristenpart, William D.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518250/
https://www.ncbi.nlm.nih.gov/pubmed/32973285
http://dx.doi.org/10.1038/s41598-020-72798-7
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author Asadi, Sima
Cappa, Christopher D.
Barreda, Santiago
Wexler, Anthony S.
Bouvier, Nicole M.
Ristenpart, William D.
author_facet Asadi, Sima
Cappa, Christopher D.
Barreda, Santiago
Wexler, Anthony S.
Bouvier, Nicole M.
Ristenpart, William D.
author_sort Asadi, Sima
collection PubMed
description The COVID-19 pandemic triggered a surge in demand for facemasks to protect against disease transmission. In response to shortages, many public health authorities have recommended homemade masks as acceptable alternatives to surgical masks and N95 respirators. Although mask wearing is intended, in part, to protect others from exhaled, virus-containing particles, few studies have examined particle emission by mask-wearers into the surrounding air. Here, we measured outward emissions of micron-scale aerosol particles by healthy humans performing various expiratory activities while wearing different types of medical-grade or homemade masks. Both surgical masks and unvented KN95 respirators, even without fit-testing, reduce the outward particle emission rates by 90% and 74% on average during speaking and coughing, respectively, compared to wearing no mask, corroborating their effectiveness at reducing outward emission. These masks similarly decreased the outward particle emission of a coughing superemitter, who for unclear reasons emitted up to two orders of magnitude more expiratory particles via coughing than average. In contrast, shedding of non-expiratory micron-scale particulates from friable cellulosic fibers in homemade cotton-fabric masks confounded explicit determination of their efficacy at reducing expiratory particle emission. Audio analysis of the speech and coughing intensity confirmed that people speak more loudly, but do not cough more loudly, when wearing a mask. Further work is needed to establish the efficacy of cloth masks at blocking expiratory particles for speech and coughing at varied intensity and to assess whether virus-contaminated fabrics can generate aerosolized fomites, but the results strongly corroborate the efficacy of medical-grade masks and highlight the importance of regular washing of homemade masks.
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spelling pubmed-75182502020-09-29 Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities Asadi, Sima Cappa, Christopher D. Barreda, Santiago Wexler, Anthony S. Bouvier, Nicole M. Ristenpart, William D. Sci Rep Article The COVID-19 pandemic triggered a surge in demand for facemasks to protect against disease transmission. In response to shortages, many public health authorities have recommended homemade masks as acceptable alternatives to surgical masks and N95 respirators. Although mask wearing is intended, in part, to protect others from exhaled, virus-containing particles, few studies have examined particle emission by mask-wearers into the surrounding air. Here, we measured outward emissions of micron-scale aerosol particles by healthy humans performing various expiratory activities while wearing different types of medical-grade or homemade masks. Both surgical masks and unvented KN95 respirators, even without fit-testing, reduce the outward particle emission rates by 90% and 74% on average during speaking and coughing, respectively, compared to wearing no mask, corroborating their effectiveness at reducing outward emission. These masks similarly decreased the outward particle emission of a coughing superemitter, who for unclear reasons emitted up to two orders of magnitude more expiratory particles via coughing than average. In contrast, shedding of non-expiratory micron-scale particulates from friable cellulosic fibers in homemade cotton-fabric masks confounded explicit determination of their efficacy at reducing expiratory particle emission. Audio analysis of the speech and coughing intensity confirmed that people speak more loudly, but do not cough more loudly, when wearing a mask. Further work is needed to establish the efficacy of cloth masks at blocking expiratory particles for speech and coughing at varied intensity and to assess whether virus-contaminated fabrics can generate aerosolized fomites, but the results strongly corroborate the efficacy of medical-grade masks and highlight the importance of regular washing of homemade masks. Nature Publishing Group UK 2020-09-24 /pmc/articles/PMC7518250/ /pubmed/32973285 http://dx.doi.org/10.1038/s41598-020-72798-7 Text en © The Author(s) 2020 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Asadi, Sima
Cappa, Christopher D.
Barreda, Santiago
Wexler, Anthony S.
Bouvier, Nicole M.
Ristenpart, William D.
Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title_full Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title_fullStr Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title_full_unstemmed Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title_short Efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
title_sort efficacy of masks and face coverings in controlling outward aerosol particle emission from expiratory activities
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7518250/
https://www.ncbi.nlm.nih.gov/pubmed/32973285
http://dx.doi.org/10.1038/s41598-020-72798-7
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