It’s official — wearing a mask not only protects others from your expelled respiratory droplets, it protects you as well, according to new guidance from the US Centers for Disease Control and Prevention.
But what type of mask will offer you and others the best protection from any novel coronavirus circulating in the air?
Medical experts advise using a minimum two-ply mask — a three-ply mask is even better.
Stay away from bandanas and gaiter masks unless that’s all that’s available. A recent study found both types to be the least effective in terms of protection.
In addition to level of filtration, pay attention to fit. You want the mask to go over the bridge of the nose, below the chin and be flush on the face, resting along the skin. You want your breath going through the filter media and not escaping out the sides.
Cloth masks with high thread counts are an excellent choice, according to the new guidance from the CDC.
Look for a tight weave of 100% cotton, according to studies. Use the light test to check the weave: If you can easily see the outline of the individual fibers when you hold up the mask to the light, it’s not likely to be effective.
You want as many layers as possible without sacrificing breathability — if you can’t breathe though it, you won’t keep the mask on your face. Two- and three-layer masks appear to do the trick for most people.
According to the CDC, “multiple layers of cloth with higher thread counts have demonstrated superior performance compared to single layers of cloth with lower thread counts, in some cases filtering nearly 50% of fine particles less than 1 micron.”
That’s good news — studies have detected SARS‐CoV‐2 in aerosols between 1 and 4 microns.
In addition, studies have found that multilayer cloth masks can block between 50% and 80% of fine droplets and particles, and “limit the forward spread of those that are not captured,” the CDC said, “with cloth masks in some studies performing on par with surgical masks as barriers for source control.”
The CDC says that polypropylene, one of the most commonly produced plastics in the world, may “enhance filtering effectiveness” because it creates a triboelectric charge — or in simple terms, static cling.
That electrical static traps both your outgoing respiration and any droplets headed your way from others. Because cotton is a more comfortable fabric on the skin, polypropylene is often used as filters that can be placed inside of a two- or three-ply mask.
Washing kills the electrical charge, but don’t worry. A brisk rub between your fingers should bring back that “clingy” charge.
A very breathable option, according to the CDC, is silk, which “may help repel moist droplets, and reduce fabric wetting and thus maintain breathability and comfort.”
A study published in September examined the ability of cotton, polyester and silk to repeal moisture when used in masks or as mask inserts.
“We found that silk face coverings repelled droplets in spray tests as well as disposable single-use surgical masks,” the authors wrote, adding that silk masks “can be more breathable than other fabrics that trap humidity, and are re-useable via cleaning.”
That brings up an important point: To avoid trapping germs that might irritate your face or reduce the mask’s effectiveness, reusable masks should be washed daily with soap and hot water. Don’t wear the mask again until it’s completely dry — it’s harder to breathe though wet fabric.
“If you use a filter in your mask, be sure to change it regularly because it can clog. You can tell if it gives you a sensation that’s a little harder to breathe,” said Emory’s Sexton.