The Best and Worst Face Masks for COVID-19 Protection
Wearing a face mask can help stop the spread of COVID-19, but some masks are better than others. A recent research study ranked various types.
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Wearing a face mask in public (especially when social distancing isn’t possible) can help reduce the spread of COVID-19. But not all masks protect equally. Some masks are more effective than others at blocking the viral droplets expelled when you cough, sneeze, speak or even breathe.
In a study from Duke University, researchers ranked 14 types of masks at how well they accomplished this task, from the medical grade N95 respirator to homemade ones. Given how serious a coronavirus infection can be, many people want to know more about which ones offer the best protection.
In the study, researchers asked participants in various types of masks to say “Stay healthy, people” five times into a box. Participants also did the same without a mask. The researchers used a laser and a phone camera to track particles released. Every mask was tested 10 times, and an algorithm determined exactly how many droplets escaped through the face coverings.
This study, which appeared in Science Advances, was not a randomized, controlled trial. It’s what is known as a proof-of-concept study, primarily designed to see if the new testing method worked.
Experts are quick to caution that any face covering is better than no face covering. Even a single-layer bandanna or neck gaiter, both of which fared poorly in the Duke study, are better than no covering at all. Read on for more details.
And the Best Face Mask Is…
No shocker here, but the medical-grade N95 respirator mask was the most effective at trapping particles. N95 respirators are known to filter at least 95 percent of airborne particles.
“This is a very high level of dust control which is why asbestos and silica workers wear N95s,” says Jack Caravanos, D.P.H., a clinical professor in NYU’s College of Global Public Health in New York City. These masks are reserved for health care personnel because the highest layer of protection is needed in healthcare settings. In daily interactions, experts say cloth face coverings and masks are enough protection, particularly when combined with social distancing.
In any case, try to avoid face masks with an exhalation valve, Caravanos warns. “These plastic valves in front of the mask make it easier to push out aerosol, so we are advising against wearing a mask with exhalation or exhaust valves,” he says. The air that exits a valve is unfiltered, so these masks protect the person wearing them, but not the people around them. The Centers for Disease Control and Prevention (CDC) also cautions against wearing masks with exhalation valves or vents.
N95s are certified to fit by the National Institute for Occupational Safety and Health. Another variety of medical-grade masks, KN95 masks, are as effective at filtering particles as the N95, but are not fitted. These are certified and regulated by the Chinese government.
“Some KN95 masks may fit really well and others pretty loose,” Caravanos says. “If you have one that fits well to your face, it will be just as effective as an N95.”
The three-ply surgical mask came in second in the Duke study but is No. 1 in Caravanos’ eyes. “They are cheap, disposable, and breathable and have multiple layers.” In the test, zero to 0.1 droplets were transmitted through these masks. The CDC cautions that these should continue to be reserved for health care workers and other medical first responders.
Choosing and Using Cotton Face Coverings
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Next up were double-layer cotton masks and those made with polypropylene, which is commonly used as a filter in face masks. Both reduced the spray from normal speech and were about as effective as standard surgical masks, the Duke study showed.
When buying a cotton mask, look for a tight-weave, 100 percent cotton, Caravanos suggests. “If it is not tightly woven, viral particles can escape,” he says. “You want at least two layers because presumably with two layers any particle that gets through the first will be caught by the second.”
The fit of any face covering matters as well. “It should be tight against your mouth with a chin curve at the bottom to prevent things from getting out,” Caravanos says.
Cotton masks don’t always have nose clips that secure the covering around your nose. That’s a problem. “It can slip down and when you exhale or inhale, and the particles can escape,” he says. This is why most public service announcements stress your face mask should cover your mouth and nose for maximum effectiveness.
“It isn’t just coughing or sneezing that spreads viral droplets; it’s also breathing, so if your nose isn’t well covered, you are basically exhaling these fine droplets,” says Manhar Dhanak, Ph.D., chair of engineering and science at Florida Atlantic University in Boca Raton, Fla. Here is how to disinfect your cloth face masks.
A face covering should block all exit routes so the only way out is through the material covering your mouth and nose. These four household products kill coronavirus, according to Consumer Reports.
The World Health Organization (WHO) says fabric masks should consist of three layers:
- An inner layer of absorbent material such as cotton;
- A middle layer or filter made of a non-woven material like polypropylene;
- An outer layer of non-absorbent material such as polyester or polyester blend.
Stock up if you use cotton or fabric masks. “It’s a good idea to have a collection of at least five so you have time to clean yours properly to get rid of germs,” Caravanos says. This will help prevent “maskne,” or acne breakouts from wearing a face covering.
Debunking ‘Gaiter Gate’
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Least effective in the Duke study were the bandana, knitted mask and neck gaiter. The study seemed to show neck gaiters actually performed slightly worse than no mask at all. Some media reports called this “Gaiter Gate.” However, the researchers noted that they tested only one type of neck gaiter, on one person, and that not all gaiters are the same.
Other researchers did further experiments and also debunked this finding. They showed that when a single-layer gaiter is worn doubled-up, it blocks a range of particle sizes. In the Duke study, the gaiter tested was not folded over. “Any face covering is better than no face covering,” Dhanak stresses.
Up next, learn how long germs last on nine not-so-common surfaces.