Is a mask with an exhalation valve effective at preventing the wearer from spreading COVID-19 to others?

Last updated: February 20, 2022
The single study in this list that examines this question found that the answer is no. A single study is often not sufficient to draw a conclusion so we encourage you to refer to this study merely as food for thought.
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Chart summary of 1 study examining this question

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SUMMARIES OF STUDIES
Total studies in list: 1
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Visualizing droplet dispersal for face shields and masks with exhalation valves
"Several places across the world are experiencing a steep surge in COVID-19 infections. Face masks have become increasingly accepted as one of the most effective means for combating the spread of the disease when used in combination with social-distancing and frequent hand-washing. However, there is an increasing trend of people substituting regular cloth or surgical masks with clear plastic face shields and with masks equipped with exhalation valves. One of the factors driving this increased adoption is improved comfort compared to regular masks. However, there is a possibility that widespread public use of these alternatives to regular masks could have an adverse effect on mitigation efforts. To help increase public awareness regarding the effectiveness of these alternative options, we use qualitative visualizations to examine the performance of face shields and exhalation valves in impeding the spread of aerosol-sized droplets. The visualizations indicate that although face shields block the initial forward motion of the jet, the expelled droplets can move around the visor with relative ease and spread out over a large area depending on light ambient disturbances. Visualizations for a mask equipped with an exhalation port indicate that a large number of droplets pass through the exhale valve unfiltered, which significantly reduces its effectiveness as a means of source control. Our observations suggest that to minimize the community spread of COVID-19, it may be preferable to use high quality cloth or surgical masks that are of a plain design, instead of face shields and masks equipped with exhale valves."
AUTHORS
John Frankenfield
Manhar Dhanakb
Siddhartha Vermaa)
PUBLISHED
2020 Physics of Fluids
High Quality Source
No
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