Double-masking can increase your protection. But not all masks should be layered.

Quicker- and easier-spreading variants of the coronavirus are making some wonder if they should upgrade their mask, or double up with ones they already own. In a question posed to Curious Philly — our platform where readers ask us questions and reporters hunt down the answers — a reader asked:

“What is better? An N95 mask or two blue surgical masks?”

We consulted local health experts, as well as the latest masking guidance from the Centers for Disease Control and Prevention, to lay out the most effective masking strategies.

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N95 masks are designed to achieve a very close facial fit and highly efficient filtration of airborne particles. Unlike cloth and surgical masks, every N95 must be tested rigorously by the National Institute for Occupational Safety and Health (NIOSH), a branch of the CDC. To get a NIOSH stamp of approval, each mask must filter out a minimum of 95% of very small particles in the air. All of this makes N95 masks the gold standard.

But, they may not be the best option for everyone. According to the FDA, you should talk to your doctor if you have chronic respiratory, cardiac, or other medical conditions that make breathing difficult because wearing a N95 mask can make it harder to breathe. If you have facial hair, you should also consider alternatives. Facial hair can prevent a proper fit, which is needed for the mask to provide full protection. Likewise, N95 masks aren’t designed to fit children.

If you do decide a N95 mask is right for you, it’s important to make sure your mask is officially NIOSH-approved. This ensures you’re purchasing an N95 mask that will provide you with the best protection. You can look for “NIOSH” or the NIOSH logo on packaging, and also the NIOSH approval number, which always starts with the letters “TC”. (Ex: TC-84A-XXXX.) But your best bet is to refer to the CDC’s list of NIOSH-approved masks, listed by manufacturer. View the list here.

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Another good mask option is the KN95. It’s the standard in China, and while KN95 masks aren’t tested by NIOSH, they’re rated to filter out 95 percent of airborne particles. “As long as you can verify that your mask is an actual KN95, and it fits properly, it will protect you better than a standard cloth mask or surgical, medical-grade mask,” says Craig Shapiro, a pediatric infectious diseases specialist at Nemours/Alfred I. duPont Hospital for Children.

Verifying that your mask is actually a KN95 is important. In the United States, 60 percent of KN95 masks are counterfeit, according to the CDC. Before making a purchase, consult the CDC’s guidance on KN95s. KN95 masks are not recommended if you have facial hair.

N95, surgical, and KN95 masks aren’t always cheap, and because they’re disposable, the price can quickly add up. If opting for a cloth mask, the CDC recommends looking for ones with multiple layers of fabric and a nose wire, a metal strip along the top of the mask. The nose wire can be bent around your nose to prevent air leaks and create a better fit. And it’s the fit of the mask that matters most.

“I would rather wear a well-fitting cloth mask than a poor-fitting surgical mask,” says Shapiro.

How do you know if you’ve got a good fit? You should feel warm air come through the front of the mask and may be able to see the mask material move in and out with each breath, says the CDC. There also shouldn’t be any gaps. Even the smallest gaps can leak respiratory droplets in the air to your nose and mouth.

You can also try securing a loose surgical mask using the CDC-recommended “knot and tuck” method. It entails tying a knot on the ear loops where they join the edge of the mask, and folding and tucking any excess material under the mask’s edges. In laboratory testing, this method was shown to substantially improve protection against exposure and transmission of the virus. Here’s a video on how to do the knot and tuck:

To increase your protection, the CDC recommends adding multiple layers of material. This can mean choosing a cloth mask that has multiple layers of fabric or double-masking with disposable and cloth masks.

If double-masking, you should wear the disposable mask underneath the cloth mask. This can be an effective way to seal a looser fitting surgical mask to your face.

Again, the fit here is crucial. If adding a surgical mask underneath your cloth mask creates gaps, this defeats the purpose. Likewise, if double-masking is uncomfortable and causing you to constantly readjust or touch your face, you’re better off wearing just one.

“Unless the masks are secure, you may actually be putting yourself at greater risk,” says Shapiro.

According to the CDC, the outer cloth mask should push the edges of the surgical mask against your face. If this affects your ability to breathe, again, stick to a single, well-fitting surgical or multi-layer cloth mask.

“If you’re able to double-mask in a way that’s safe and it doesn’t impact your ability to breathe, then I’d absolutely support that, but I don’t want anyone to feel like they must wear two masks at the expense of their own health,” says Shapiro.

It’s important to note that not every type of mask can be layered effectively.

The CDC hasn’t yet released guidance on wearing two cloth masks or the efficacy of doing so.

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Masks are critical for preventing the spread of COVID-19. And the good news is that research is uncovering ways to improve mask usage for better protection. This, however, doesn’t negate the importance of other protective measures, especially getting vaccinated.

As for masking, again, what matters most is mask fit. “At the end of the day, it’s the proper fitting of the mask that’s going to make me more comfortable,” says Goldstein.

This article has been updated since it first published.

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