Your Face Mask Should Ideally Have 3 of These, Experts Say

New guidelines say this is what your mask needs to provide the best defense against COVID.

It's widely agreed upon by medical experts and government officials alike that wearing a face mask when you're out in public or in close proximity to others is an effective method of slowing the spread of COVID-19. What may be somewhat less common knowledge is the varying levels of protection—or, in some cases, the utter lack of it—provided by the different types of masks being used. To provide some clarity on that matter, the Association of American Medical Colleges (AAMC) released a set of guidelines for when, where, and which face masks are most effective. Among their recommendations, the AAMC advises that if you want the most durable defense against the virus your cloth face covering should ideally have three protective layers.

According to the AAMC, studies have shown that a two-layer cloth face covering was significantly better than a single-layer mask when it comes to limiting the spread of droplets expelled by coughing and sneezing, but specifically noted that using one that has three layers "whenever possible" is even better. And research recently published in the journal Science Advances supports the AAMC's recommendation. After testing 14 different masks' ability to block respiratory droplets, professors from Duke University found that other than the N95, which should be reserved for frontline medical workers, a three-layer surgical mask allowed the fewest number of droplets to get by its barrier. Coming in third? A three-layer mask with polypropylene as filter between two layers of cotton.

a young woman in a yellow sweater wearing a surgical mask

In another study published in the journal Thorax, a team of Australian researchers came to the same conclusion, stating that their findings indicate that a home-made cloth face mask needs a minimum of two layers to be effective at blocking viral droplets, but three layers is highly preferable.

The AAMC's guidelines also stated that bandanas and other loosely folded cloth coverings provide the least amount of protection, but are better than no face mask at all. In addition, they stressed the importance of wearing a face mask when indoors, as well as in nearly all outdoor situations where other people are around.

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"These guidelines are meant to provide everyone around the country with a unified approach to wearing face masks and correct the often-conflicting messaging and misinformation out there," Atul Grover, MD, PhD, executive director of the AAMC Research and Action Institute, said in a statement. "Until we develop a vaccine and better therapeutics, prevention is the key to reducing the impact of this pandemic. The quicker we make face coverings our 'new normal,' the faster we can gain control over COVID-19." And for more on slowing the spread of coronavirus, This New COVID Defense is "More Effective" Than Your Mask, Scientist Says.

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