How Effective are Face Masks Against COVID Infection?

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How effective are your face mask-wearing habits at reducing the spread of COVID? Risk Bites takes a look at the science of what works better, and when.

For more information and links to further resources, please do check out the links below.

This video was produced in collaboration with Dr. Lisa Brosseau at the University of Minnesota, who has led research on the relative impacts of different mask-wearing scenarios.

NOTES

This Risk Bites video draws on research by Dr. Brosseau and others on how different masks extend the time before the risk of infection becomes substantial when two people are in close proximity, and one has COVID.

The research builds on the Centers for Disease Control and Prevention guideline of a 15 minute “window of safety” when in close proximity to someone with COVID and no masks are being worn. However, it is important to realize that, while this 15 minute guideline is useful, it is not based on scientifically sound data, and so is more of a suggestion than a hard and fast rule.

What is important though is how this “window of safety” increases with different mask wearing behavior.

In this video we don't explicitly address the widely-used K95 masks. These are not to be confused with NIOSH approved N95 respirators. However, they do provide higher filtration efficiency than surgical masks, and most KN95s allow a better seal to be achieved between the mask and the face, if worn correctly.

However, an important factor in mask leakage is how the mask is held on. Ear loops such as those found on many K95s do not ensure a good seal – as anyone who has struggled with their glasses fogging up while wearing one will know.

Masks that use multiple bands that go round the back of the head typically allow a better seal to be achieved.

USEFUL LINKS

COVID-19 respiratory protection – resources from the University of Minnesota

How Face Masks Work (YouTube):

ACGIH COVID-19 Fact Sheet: Workers Need Respirators

Information on respirator fit testing (NIOSH):


RISK BITES

Risk Bites videos are devised, created and produced by Professor Andrew Maynard. They are posted under a Creative Commons License CC-BY-SA

This video was devised and produced in collaboration with Dr. Lisa Brosseau

Backing track:

Sunny Breakfast, by Dominik Schwarzer. Used under license from Premium Beat

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ANDREW MAYNARD
Andrew Maynard is a scientist, author, and leading expert on risk and the ethical and socially responsible development and use of new technologies. He is an elected Fellow of the American Association for the Advancement of Science, serves as co-chair of the Institute for the Advancement of Nutrition and Food Science (IAFNS) Board of Trustees, is a member of the Canadian Institute for Advanced Research President’s Advisory Council, and has served on a number of National Academies of Sciences committees. He is a Professor in the Arizona State University School for the Future of Innovation in Society where he studies the future and how our actions in the present affect it.
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LISA BROSSEAU
Lisa Brosseau is a Research Consultant at the University of Minnesota, Center for Infectious Disease Research and Policy, and an Industrial Hygienist certified by the American Board of Industrial Hygiene and Associate Faculty of Occupational Hygiene in the British Occupational Hygiene Society. She is a leading expert on respiratory protection, aerosol measurement, filtration performance, and small business health and safety.

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#covid #facemask #respirator