Face masks are much more than a symbol. Over the last year, we’ve learned that countries and regions that encourage or require masking seem to do better at slowing the spread of COVID-19 than places that don’t, and new evidence suggests that masking may protect both the wearer and the people around them.
Many TIME readers have recently reached out with questions about masks—which kind of mask should they wear? How do they wear them correctly? Should they be double-masking? And so on. So we asked the masking experts for tips based on the latest research.
Is It Time to Upgrade Your Mask?
Early in the pandemic, many of us bought cloth masks to help reduce spread while reserving more effective, medical-grade masks for people at higher risk, like doctors, first responders and so on. But a year in, with increased mask production and a growing number of people vaccinated, is it time for us to upgrade our masks?
Indeed, experts say the best face coverings are respirator-style masks, like N95s. These masks are approved by the U.S. National Institute for Occupational Safety and Health (NIOSH); the “95” means the mask filters at least 95% of particles out of the air the wearer is breathing in.
However, there are two main problems with N95 masks.
First, respirator masks remain in short supply—even some health care facilities are still having trouble getting enough of them. Although supply has increased since the beginning of the pandemic, that’s partly because health care workers are still taking unusual steps to conserve supply, like wearing a single mask all day long or even reusing masks across more than one day.
Given that, another surge in COVID-19 cases could trigger a respirator shortage, says Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota who was a member of President Joe Biden’s transition COVID-19 Advisory Board. “If we see a surge in cases like might happen with B.1.1.7, we could go through [respirators] very quickly again,” says Osterholm, referring to an especially transmissible variant first identified in the U.K. and which has since been detected in the U.S. “So it is very important that we try to reserve those as much as we can.”
Second, people who wear respirators are supposed to be fit-tested annually to make sure their mask provides a good seal around their face. Respirators come in different styles and sizes, and whether you fit in a particular model can change over time. Without fit-testing, there’s no way to know for sure that you’re getting anywhere near the advertised protection level.
However, if you can get your hands on respirator masks and you’re careful about their fit (see below), they can provide a “big upgrade to your current mask setup,” says Linsey Marr, a professor of civil and environmental engineering at Virginia Tech. Marr advises that wearers should throw their mask out if they see any damage to the material, or if the straps begin to weaken.
Other potentially effective medical masks include U.S. Food and Drug Administration-approved surgical masks (disposable masks which fit more loosely) and foreign-made respirator masks, including KN95s (from China) and KF94s (from South Korea)—but they also come with a few caveats. Surgical masks are more likely than respirator masks to have gaps big enough to allow air to leak through the side. KN95s and KF94s, meanwhile, can be hit or miss. While they work similarly to N95s, such masks have not been fully approved by NIOSH (although some KN95s manufacturers have received emergency use authorization from the agency). Meanwhile, the U.S. Centers for Disease Control and Prevention warns that most products that claim to meet European or Chinese standards provide “well below 95%” filtering efficiency. Furthermore, at least some of the N95s, KN95 and KF94 masks on the market are likely counterfeit and provide inadequate protection, and it’s difficult for most buyers to tell a counterfeit mask from a real one, especially when shopping online.
Sticking With Cloth
For people who can maintain physical distance from others, cloth masks may still be the best bet for daily use, experts say. “Even a simple cloth mask, if it’s made out of a tightly woven material and fits well, protects others and can protect the wearer,” says Marr.
However, cloth masks can vary widely in their efficacy. Experts suggested a well-fitting, three-layer mask, with an outer layer that’s tightly woven or even waterproof and with either a built-in filter or a pocket for replaceable filters as the middle layer. A filter made of non-woven polypropylene, a HEPA-grade filter or even a patch of material cut out of a vacuum-cleaner filter are all good options, says Marr. Even a piece of tissue or paper towel can serve as the middle layer, say Amy Price and Dr. Larry Chu, Stanford University professors who helped develop the World Health Organization’s masking guidelines. Finally, the inner layer touching your skin can be made of soft cotton.
Price and Chu suggest applying static electricity to all of your cloth mask’s layers—the cloth inner and outer, as well as the paper layer or filter—by putting on latex gloves, rubbing your hands together, and then rubbing each later before every time you put it on. This, he says, says can increase the mask’s particle-filtering efficacy, and the effect lasts for several hours. “Research that came out of work that we did with our colleagues at Stanford showed that static electricity can actually really improve the filtering capacity of masks,” says Chu.
Check the Fit
Whether you have a respirator mask or a cloth mask, fit is essential, says Dr. Krutika Kuppalli, an assistant professor of medicine at the Medical University of South Carolina. “It should go across the bridge of your nose, it should form a seal across your nose and go under your chin. It should lay flat against your cheeks,” she says.
You should look for two features in a mask to ensure it can offer the best possible fit: a metal bridge that you can seal around your nose, and fasteners that keep your mask tight around your face and allow you to adjust the fit. If you choose to wear a medical procedure mask (commonly called surgical masks), the U.S. Centers for Disease Control and Prevention has found that knotting the ear loops where they meet the mask and then flattening the front of the mask can reduce exposure by nearly 96%, assuming two people interacting with one another are both wearing such ‘knotted’ masks.
And make sure to wear your mask properly, of course.
“I think the most common kind of poor masking practice I see is the mask…hanging off the nose so that the nose is sticking out,” says Marr. “So there you lose the benefit of the mask almost completely, especially for your own protection, because you’re probably breathing through your nose and there’s nothing covering your nose.”
Keep It Clean
After you remove your face mask, you should treat it like a stinky pair of socks, says Lisa Brosseau, a research consultant for the Center for Infectious Disease Research and Policy at the University of Minnesota.
Experts suggest washing or sanitizing your hands after you touch your mask; keeping your mask in a paper or plastic baggie when not in use; and carrying back-up masks with you instead of putting a dirty mask back on your face after you’ve removed it.
If you have a washable cloth mask, the CDC advises washing it whenever it gets dirty, and “at least” daily. Masks that can’t be washed, like respirators, can be left out in the sun for an hour to be decontaminated, Marr says. However, it’s important to remember that these masks are intended to be disposable; in professional settings, NIOSH recommends that people follow the respirators manufacturer’s recommendations, or wear the mask no more than five times.
What About Double-Masking?
For further protection, you may want to consider “double-masking”—putting one mask over the other. Wearing a cloth mask over a medical procedure mask can reduce people’s exposure by as much as 96.4% when two people interacting with one another are both double masked, the CDC found, if both people double-masked. However, getting a good fit is critical when you double mask, as adding multiple layers could create gaps between the masks. Marr suggests layering a cloth mask on top of a surgical mask, but cautions people against going overboard.
“You have to be careful once you start adding more and more layers because it can be hard to breathe through, and then then you’re going to end up pulling in more air through any gaps around the sides,” Marr says. “So there’s definitely a point of diminishing returns. I wouldn’t really go more than two layered on top of each other.”
Because double-masking can be uncomfortable, Chu suggests people do it when they’re in a more high-risk situation, like “when they’re in the subway car, when they’re in those closed public spaces, and they don’t know if they’re going to be around somebody who could potentially be carrying the new variants,” he says.
No Mask Is Perfect
While masks are an important tool to reduce the spread of COVID-19, they can’t guarantee you total protection. Instead, it’s better to think of them as just one more thing you can do to keep yourself and the people around you safe—in addition to avoiding indoor spaces with poor ventilation, keeping away from crowds and close contact with other people, and trying to stay at home as much as possible.
“We expect too much of face coverings,” says Brosseau. “We expect that we can go out, and they will protect us and protect the people around us for long periods of time, or when we’re up close and personal with people for long periods of time. And they will do a little bit, but not as much as we think they will.”