December 7, 2020 By Off

The best and worst face masks, ranked by their level of protection

The science is clear: Face masks can prevent coronavirus transmission and save lives.

A preliminary analysis of 194 countries found that places where masks weren’t recommended saw a 55% weekly increase in coronavirus deaths per capita after their first case was reported, compared with 7% in countries with cultures or guidelines supporting mask-wearing. A model from the University of Washington predicted that the US could prevent nearly 67,000 coronavirus deaths by December if 95% of the population were to wear face masks in public.

But not all masks confer equal levels of protection.

The ideal face mask blocks large respiratory droplets from coughs or sneezes — the primary method by which people pass the coronavirus to others — along with smaller airborne particles, called aerosols, produced when people talk or exhale.

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The World Health Organization recommends medical masks for healthcare workers, elderly people, people with underlying health conditions, and people who have tested positive for the coronavirus or show symptoms. Healthy people who don’t fall into these categories should wear a fabric mask, according to WHO. The Centers for Disease Control and Prevention also recommends cloth masks for the general public.

But even cloth masks vary, since certain types are more porous than others.

“It depends on the quality,” Dr. Ramzi Asfour, an infectious-disease physician in Marin County, California, told Business Insider. “If you’re making a cloth mask from 600-thread-count Egyptian cotton sheets, that’s different than making it from a cheap T-shirt that’s not very finely woven.”

Over the past few months, scientists have been evaluating the most effective mask materials for trapping the coronavirus. The most recent research, published by Duke researchers last week, found that using polyester spandex neck fleeces as face coverings may actually increase the rate of droplet transmission during speech. Here are the results of the best studies on masks so far, with materials from most to least protective.