How to Reuse Your KN95 or N95 Mask Safely

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It might be time to level up your mask game. With the highly contagious Omicron variant around, the CDC may soon recommend trading in your cloth masks for higher-quality KF94, N95, and KN95 masks, which feature several layers of filtration to block up to 95 percent of particles from reaching your mouth and nose.

The downside to these highly protective masks is that they're not quite as reusable as cloth masks, which can be washed and reworn time and time again. And since they're often priced at about $1 to $2 per mask (and prices are on the rise), replacing your N95 or KN95 mask every time you're out and about can start impacting your finances—even while it's protecting your overall health.

Fortunately, you can safely reuse your N95 and KN95 masks for a while before it's time to toss them out. "The filter material is so high performing that even with 40 hours of use, I haven't seen issues with filtration," says Aaron Collins, a mechanical engineer who runs the Mask Nerd YouTube channel, posting videos of mask aerosol tests and other mask fit information. "Even after loading the mask with aerosol, they're still high performing."

RELATED: How to Avoid Buying Counterfeit KN95 Masks

But there are a few things you'll need to keep in mind to help you get the most out of every mask—and keep yourself as safe as possible.

Think about how you're using your masks

A mask you're only donning for a quick trip into a grocery store can probably last for several weeks' worth of trips. But if you're wearing it for longer stretches or dirtier activities (like a sweaty workout at the gym), you may need to swap them out faster. "They can last for quite a long time—at least five days under health care conditions," says Lisa Maragakis, MD, MPH, senior director of infection prevention and professor of medicine at Johns Hopkins. "And in normal use conditions, they could last even longer."

In the mask tests conducted by Collins, the mask filters lost only 1 percentage point of effectiveness after logging 40 hours of wear. But that's when other things started to go wrong with the mask. "They get a little stanky, and the ear loops and mask itself start to lose structure," Collins says.

Give your mask a break

If your mask has been exposed to COVID, it could conceivably live on the exterior of the mask for a few days. A paper in the Journal of Emergency Medicine recommends leaving masks aside for three to four days to allow the mask to air out and any contaminants to die off. That time off also allows your mask to dry out a bit—they can get damp from sweat or moisture from your breath.

Store your masks appropriately

The key thing for storing a KN95 or N95 mask between uses is avoiding anything that's too sealed—a plastic baggie, for instance, would be a bad idea as it won't allow any moisture that's built up in the mask to dry out and escape.

Early in the pandemic, health care workers often stored their masks in paper bags to allow them to dry out between wears. A plastic container with the lid slightly opened could also work. And Collins opts to store his child's on a set of hooks, with a pair of masks for each day of the week.

Keep the mask somewhere where it's protected. If the mask gets crushed or folded, you could be reducing its effectiveness. "The filtration comes from the physical structure, so you don't want to crush or fold it," Dr. Maragakis says. "Folding it disrupts the structural integrity of it."

Watch for signs of wear

Any rips, tears, or holes are an obvious sign that it's time to toss out your mask. If the mask structure starts to soften and the elastics stretch out, that's another signal that it's time to make a change.

Makeup stains or workout sweat won't impact the effectiveness of the mask, but may feel a little gross to put back on. "One researcher soaked N95 respirators in artificial sweat, and it didn't affect the filtration," Collins says. "So light soiling from makeup or sweat isn't going to be a big issue."

Don't wash your KN95 or N95 masks

It seems so tempting to just swab your KN95 mask with alcohol or throw it in the washer to get it fresh and clean. But doing that can drastically decrease a mask's effectiveness. "Alcohol will damage the electrostatic charge," says Collins. That charge helps the mask filter out contaminants, so you definitely don't want to lose it.

There are some tips out there about ways to clean the masks, but Collins says it's better to just move on to your next mask instead. "Dry heat, baking, sanitization—all of those things can be done, but if your oven overshot the temperature, that could damage the filter medium, and you wouldn't even know it. Keep it simple, and just let them sit out."

Watch the fit

"Fit is fundamental," Collins says. "The mask is the filter, and you need to make sure air goes through, not around it. If you start losing fit, you're losing protection."

You should not feel cooler air coming across your face around the edges of the mask—that may indicate you don't have a great fit.

Don't ditch your cloth masks entirely

While the N95s, KF94s, and KN95s may provide optimal coverage, they can often be less comfortable to wear—which can lead many people to stop wearing masks altogether. If you can't find an KN95 or N95 that works for you, wearing a cloth mask can still reduce your COVID risk.

"I think there's a bit of misplaced emphasis on upgrading the mask," says Dr. Maragakis. "I think cloth masks have saved many lives. The most important thing is just to wear masks, and wear them consistently, wear them properly. That's the most important thing we can do to bring this surge to an end."