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Making masks fit better can reduce coronavirus exposure by 96%

Science desk || shiningbd

Published: 13:13, 13 February 2021   Update: 13:25, 13 February 2021
Making masks fit better can reduce coronavirus exposure by 96%

Masking can reduce the spread of the coronavirus, especially when everyone wears them, and when the masks fit well, new research suggests. VLADIMIR VLADIMIROV/E+/GETTY IMAGES

By now, most people have gotten the message that wearing a face mask is one way to help stop the spread of COVID-19. But now health officials are taking the masking message a step further: Don’t just wear a mask, wear it well.

Taking steps to improve the way medical masks fit can protect wearers from about 96 percent of the aerosol particles thought to spread the coronavirus, a study by the U.S. Centers for Disease Control and Prevention found. That’s provided both people are wearing masks. But even if only one person is wearing a mask tweaked to fit snugly, the wearer is protected from 64.5 percent to 83 percent of potentially virus-carrying particles, the researchers report February 10 in Morbidity and Mortality Weekly Report.

“I know some of you are both tired of hearing about masks, as well as tired of wearing them,” CDC director Rochelle Walensky said February 10 during a White House briefing. But scientists have learned in the past year how effective masks can be to protect people from catching COVID-19, she said. “The bottom line is this: Masks work, and they work best when they have a good fit and are worn correctly.”

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That message is increasingly crucial as more transmissible coronavirus variants — including ones first detected in South Africa and the United Kingdom — are beginning to spread more widely in the United States (SN: 2/5/21).

Plenty of studies have already demonstrated that masks cut down on the number of spit particles that may spray others when a person breathes, talks, coughs or sneezes (SN: 6/26/20). Still, photos and videos show that air and droplets often escape from the tops, sides, and bottoms of ill-fitting masks. “Even a small gap can degrade the performance of your mask by 50 percent,” says Linsey Marr, an environmental engineer at Virginia Tech in Blacksburg.

Good masks have both good filtration and a good fit, she says. “Good filtration removes as many particles as possible, and a good fit means that there are no leaks around the sides of your mask, where air — and viruses — can leak through.”

Several recent studies have demonstrated that some pretty simple measures to improve fit also cut down aerosol emissions. Those measures include using ear savers, pantyhose or mask fitters, or putting a cloth mask over a medical mask.

Those studies showed that wearing a mask protects other people from what the wearer spews out. But John Brooks, an infectious diseases physician and the chief medical officer for the CDC’s COVID-19 emergency response, and colleagues wanted to know whether those tricks to make masks fit better had any effect on protecting the mask wearer.

So the researchers set up two manikins facing each other six feet apart. One manikin served as the source, “exhaling” via a tube aerosol particle of saltwater of a size that could carry the coronavirus. (No viruses were used in the experiment.) The other manikin was the receiver.

The researchers measured how many saline droplets reached a mouthpiece in the receiving manikin that represented its nose and throat. In some experiments, the team put medical masks on just one of the manikins. In others, both wore masks. The team tried two scenarios to make the mask fit better: knotting the ear loops close to the mask and tucking in the ends to eliminate side gaps, and wearing a cloth mask over the medical mask.