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Will your cotton mask prevent coronavirus spread? New study casts doubt

A small study suggests we shouldn’t let masks lull us into a false sense of security.

Will your cotton mask prevent coronavirus spread? New study casts doubt
[Source Image: Ekaterina_Vitchenko/iStock]

In the midst of the coronavirus crisis, one of the biggest debates is around masks: what type is best, do they work, should you wear them? There doesn’t seem to be a consensus, and new research could further muddle the issue.

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Last Friday, the Centers for Disease Control recommended that Americans wear cloth masks when going out in public. Research has shown that people who don’t exhibit any COVID-19 symptoms may still carry the virus and spread it to others. The new recommendations are intended to prevent these people from unwittingly infecting others—the idea being that a fabric mask could catch and absorb coronavirus-laden droplets so they don’t land on another person or surface.

There’s only one problem: It’s unclear whether cotton masks or even surgical masks effectively prevent droplets of the virus from spreading from the wearer into the environment. One study from South Korea suggests that these masks might not be particularly effective at preventing the spread of the disease.

In the study, which was just published in the Annals of Internal Medicine, researchers looked at two hospitals in Seoul where COVID-19 patients wore either cotton or surgical masks. The researchers asked four patients with confirmed cases of COVID-19 to cough five times each into a petri dish while wearing no mask, a surgical mask, and a cotton mask. Then, the researchers analyzed the outer and inner surfaces of the mask. They found COVID-19 particles on every surface they tested.

It’s hard to draw wide-ranging conclusions from such a small sample size. Other studies have shown that even rudimentary face masks caused a decrease in the spread of the flu virus in crowded settings. The researchers in those studies concluded that any mask is marginally better than wearing nothing at all. And in fact, even this study showed that wearing a cotton mask lessened the viral load of the particles that ended up in the petri dish.

This new study from Korea reinforces the fact that we should be cautious about placing too much faith in cotton and surgical masks as a way to curb the spread of the coronavirus. Some DIY mask designs have pockets for people to include HEPA filters, such as those used in vacuum filters, in an effort to filter out more particle. N95 masks are the gold standard, as they filter out 95% of particles, but they’re in short supply so should be reserved for medical professionals.

The CDC says that social distancing is the most effective way to prevent spreading the disease, along with proper hand hygiene. It recommends wearing masks only when social distancing measures are difficult to maintain, such as at grocery stores and pharmacies. But studies such as this one suggest that we shouldn’t allow masks to lull us into a false sense of security. Even in these settings, people should continue to be vigilant about staying six feet apart and using hand sanitizer frequently.

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About the author

Elizabeth Segran, Ph.D., is a staff writer at Fast Company. She lives in Cambridge, Massachusetts

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