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Double Up for the Best Benefit from Face Masks

To protect yourself from airborne coronavirus, double up your face masks. That also helps protect others if you are infected.
Double Up for the Best Benefit from Face Masks
Double mask on the face. A girl in half a turn, with two masks on her face and a blue medical glove on her left hand, in the winter on the street

Speeding up vaccination as much as possible will help bring an end to the COVID-19 pandemic. Unfortunately, that may still be months if not more than a year away. Vaccination rates will need to reach significant levels throughout the world to bring the coronavirus to a halt. In the meantime, though, we have low-tech ways to prevent viral spread. Face masks, along with hand-washing, maintaining distance and avoiding crowded indoor spaces work. Moreover, they are equally effective against the scary new variants of the coronavirus. A new study from the CDC shows that face masks work much better if you double up.

What Is the Evidence to Support a Double Up on Face Masks?

Double up in this case has a double meaning. First, face masks work much better if both people in an encounter are wearing them properly. (That means wearing the mask to cover both nose and mouth throughout the interaction.) Even if one of those individuals were infected, a mask reduces the amount of virus that spreads into the air. If the other person also wears a mask, it will keep coronavirus-carrying aerosol from penetrating. It doesn’t have to be perfect to greatly reduce the infectious dose.

But to make the masks on both of these individuals work even better, double up. The alternative: figure out how to make them fit more tightly. When gaps around the edge of the mask let air escape, aerosol from your breath can also get out. If your breath is fogging your glasses, for example, your mask is leaking. Instead, wearing a cloth mask over a disposable surgical mask can dramatically reduce the amount of air that is released without filtration.

The CDC Studied How to Double Up on Face Masks:

Scientists at the US Centers for Disease Control and Prevention conducted experiments to evaluate face masks (MMWR, Feb. 10, 2021). They used dummies (to simulate the shape of a person’s head) to assess how well masks worked to stop particles from a simulated cough. The masks were a three-ply surgical mask, a three-ply cotton mask and the combination of those two. While each of these masks alone blocked just a bit more than 40 percent of the particles generated by a cough, when the cloth mask was used on top of the surgical mask, 92 percent of particles were stopped. In the experiment, when both the source and the receiver were wearing double masks, the exposure of the receiver was reduced by 96 percent.

Better Fitting Masks:

Further experiments showed that adding mask fitters to help the mask fit closely to the face dramatically boosted the efficacy of the mask. That would be an alternative if you did not want to double up. Some people may find it helpful to knot the ear loops and tuck in the gaps of a surgical mask to increase its impact. Others may not be that handy. Alternately, they may not find that knotting or tucking actually closes a gap formed by an exceptionally narrow face or a beard. Covering a single mask with a nylon loop made by cutting the leg of a pair of panty hose is a different way to double up. This also improves how well a mask fits and greatly cuts down on the amount of virus than can be sent into the air.

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About the Author
Terry Graedon, PhD, is a medical anthropologist and co-host of The People’s Pharmacy radio show, co-author of The People’s Pharmacy syndicated newspaper columns and numerous books, and co-founder of The People’s Pharmacy website. Terry taught in the Duke University School of Nursing and was an adjunct assistant professor in the Department of Anthropology. She is a Fellow of the Society of Applied Anthropology. Terry is one of the country's leading authorities on the science behind folk remedies. .
  • Brooks JT et al, "Maximizing fit for cloth and medical procedure masks to improve performance and reduce SARS-CoV-2 transmission and exposure, 2021." MMWR, Feb. 10, 2021.
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