- The CDC now says double masking can help prevent the spread of COVID-19.
- New research shows that tight-fitting, multi-layer masks provide more protection against respiratory droplets, which drive the spread of COVID-19, than less secure options.
- Doctors explain the reasoning behind wearing two masks—plus how to ensure that your mask meets the new standards.
One face mask might not cut it anymore; according to new research from the Centers of Disease Control and Prevention (CDC), you’re better off with two if your single mask does not fit properly or have multiple layers.
On February 10, the CDC released research that found wearing cloth face coverings over surgical masks, as well as tying knots on the ear loops and tucking the sides of disposable masks, offers greater protection against COVID-19 than wearing a fabric covering or a poorly-fitted medical mask alone.
We’ve known for months that face masks protect both the wearers and the people around them, and that multiple layers of tightly woven fabric offer greater protection than flimsier coverings made of loose or non-breathable material. But this is the first concrete data on double masking, and it backs up the practice that’s already been in use by everyone from essential workers to high-profile politicians to Dr. Anthony Fauci.
As new, more contagious variants of the novel coronavirus spread across the United States, wearing a face mask correctly is crucial—and doubling up may be more important than ever as we wait for a vaccine that’s widely available. Here’s what you should know.
Why is double masking more protective against COVID-19 than wearing one flimsy mask?
The CDC study tested common face coverings in a lab setting to see how well they block respiratory particles. Researchers simulated coughing and breathing between pairs of dummies with no masks, three-ply surgical masks, three-ply cloth masks, cloth masks layered over surgical masks, and surgical masks with tied ear loops and tucked sides. The results suggest that fit and filtration should be optimized in every mask.
When an infected dummy coughed, unknotted medical masks and solo cloth masks kept just 42% and 44% of particles from escaping into the air, respectively; double masking blocked 93%. Exposure to droplets from an unmasked source was reduced by 65% with a knotted and tucked surgical mask and 83% with a double mask. When both dummies were wearing double or knotted and tucked surgical masks, droplet exposure dropped 96% from unmasked levels.
“Double masking adds an extra layer of filter, making it even more difficult for the drops of moisture ridden with the virus to get to you or to spread to others,” says Aline M. Holmes, D.N.P., R.N., a clinical associate professor at the Rutgers University School of Nursing. The same goes for creating a firm seal around the mouth, cheeks, and nose, which minimizes the amount of unfiltered air that is allowed to escape from (or into) your mask.
When you go into a public space, you almost never know which you’ll be—the infected person or the exposed person. Better-fitting masks and layered masks work remarkably well in both situations, especially when combined with social distancing and hand-washing, the other major tenets of disease prevention.
“There are three big pieces that are important when it comes to properly masking: multiple layers, a good fit, and wearing a mask consistently,” says Christopher Sulmonte, M.H.A., project administrator at the Johns Hopkins Biocontainment Unit, which cares for patients with highly contagious diseases. “By utilizing these in tandem, in a balance, they can be really effective in reducing the spread of COVID-19.”
Which types of face masks are most effective for double masking?
To properly double mask, simply layer a cloth face mask over a disposable surgical mask—this is the order that the CDC recommends. The agency does not recommend wearing two disposable masks if one fits properly or layering a KN95 mask with any other type of covering, as these should suffice on their own.
How can I make sure my mask fits properly?
The CDC also offered new information on what to look for in a mask that fits well. Here’s what to prioritize (or add) when picking a face covering:
- Nose wire: That metal strip across the top of your mask allows you to create a tight seal around your nose, preventing unfiltered particles from escaping. Many masks have them already built in, but you can also order adhesive nose wires to attach to your favorite mask.
- Multiple layers of fabric: Although the CDC still says that two-layer masks are fine, they used three-layer masks in the study. To stay on the safer end, look for cloth and disposable masks with at least three layers of tightly woven, breathable fabric.
- Mask fitter: To create a better fit, the CDC also recommends adding an external fitter or brace to any mask. They should wrap around the outside of your mask, not fit on the inside like mask brackets.
You can tell if your mask has a poor fit or too few layers with a few simple tests. Sulmonte recommends holding your mask up to the sun to ensure that little to no light passes through. On a cold day, if you can see your breath extending more than an inch from your face, that’s a bad sign. And if you wear glasses and they fog up when you’re using your face covering, your breath is likely escaping from the top of your mask.
To improve the fit of a surgical covering, fold your mask in half lengthwise, then knot the ear loops as close as possible to the main part of the mask. After that, tuck the extra fabric below the knot on each side. (Watch detailed instructions here.)
Where and when should I double mask?
“Masking is not a one-size-fits-all approach,” Sulmonte explains. It all depends on your exposure—if you’re in a space where social distancing is possible, especially outside, then your go-to mask might do the trick on its own. But in a crowded, lengthy, or indoor situation, double masking is the way to go, as long as you’ll be able to see and freely breathe through your masks the entire time, he says.
Grocery stores, public transportation, and other high-traffic spaces are ideal for double masking. The same goes for people in high-risk settings, Dr. Holmes explains, like hospitals and nursing homes.
But most of all, the experts we talked to stress that any mask is better than no mask. “If the option is no mask at all, we want you to wear something,” Sulmonte explains. So if you pull up to the grocery store and realize you forgot your double masking setup, don’t sweat it—just make sure you’re wearing at least one mask that fits well, and try to remember the other one next time.
Wearing two face masks doesn’t mean you can stop social distancing from people outside of your household or washing your hands thoroughly and frequently, either, says infectious disease expert Amesh A. Adalja, M.D., senior scholar at the Johns Hopkins Center for Health Security. “If you’re doubling up your mask and still engaging in risky behavior,” he says, “that’s not going to help you.”
Additional reporting by Korin Miller
This article is accurate as of press time. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus develops, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news. Always talk to your doctor for professional medical advice.
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