How to Reuse N95, KN95, and Other Disposable Masks

Nov 24, 2023

Published January 20, 2022

Joanne Chen

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The Centers for Disease Control and Prevention recently updated its mask recommendations to align with what experts and many other people have long known: N95s and other respirator masks (when they are legitimate and fit properly) are more protective than most cloth face masks are. But these disposable respirator masks cost $1 to $3 apiece, and throwing them out as quickly as you would paper cups can add up, especially if you’re masking your entire family. You might also be concerned about the environmental cost of disposable masks, which are constructed from nonrecyclable materials. Fortunately, for most people and in most situations, you don't need to chuck your mask after each use, or each day. Here are some answers to common questions about reusing your disposable mask.

You can re-wear a mask after you have stored it in a paper bag for a few days, according to the CDC and multiple experts we’ve interviewed for our respirator guide. The agency provides a simple strategy for healthcare workers that involves rotating used masks in brown paper bags, a variation of which was employed during the N95 shortage in the early days of the pandemic. The coronavirus has an expected survival time of about 72 hours, so waiting for, say, five to seven days should be enough time for it to be inactivated.

Personally, to keep track, I have five masks on rotation and seven brown paper bags marked with the days of week, lined up on my windowsill. I place my mask in the appropriately labeled bag between uses during the day and at the end of it. After a week has passed, I either take the mask out to wear or move it to an eighth bag marked "Ready to Use."

Yes, reusing a mask is safe. Masks work the same way on any variant—by trapping virus-containing particles in their layers. Also, the coronavirus is transmitted mainly through respiration; you’re less likely to catch it by touching an infected surface. That said, it's safest, and just good hygiene, to handle your masks with care, touching only the elastics and washing your hands afterward.

Moisture, even from your breath, degrades the mask little by little, and that process will probably hasten if you’re wearing the mask to work out at the gym or if you’re in a humid room or climate. If your mask is wet due to condensation from breathing, you can reuse it. Keeping those paper bags in a dry spot (ideally by a sunny window) can help enhance the viral-deactivation process, said Christopher Sulmonte, project administrator at the Johns Hopkins Biocontainment Unit, a facility for patients with emerging infectious diseases. If your mask gets drenched (say, you get caught in the rain), throw it away.

Though you may be tempted to rinse or wash your used disposable mask, even just to freshen it up, don't try it. Getting the mask wet or agitating the mask with soap can damage the material.

You also shouldn't attempt to disinfect your used mask with alcohol, hydrogen peroxide, or other chemicals. A 2020 Emerging Infectious Diseases research letter reported that treating a disposable face mask with alcohol reduced the mask's integrity and therefore its filtration efficiency. Hydrogen peroxide worked better, but the researchers applied it using a specialized machine, something you wouldn't find outside a lab or hospital setting. Bleach or other disinfectants are a bad idea, too: Not only would they damage the mask, but "you don't want to risk breathing in any disinfectant that remains on the respirator," said Nikki Vars McCullough, a vice president at 3M's Personal Safety Division.

That same paper published in 2020, amid the N95 shortage, found that dry-heat decontamination can be effective only one or two times, and UV for three times, before the mask's fit and filtration may be compromised. Although these methods may be important in medical settings highly exposed to COVID-19 during a respirator shortage and in need of techniques to immediately zap away viruses, they require a strict protocol that's impossible to follow for most people outside of a healthcare setting. You’re better off using the paper-bag method. "It's a lot easier, less expensive, and there's less of a chance that you’ll be hurting the mask," said Sulmonte.

"There's no hard and fast rule," said Sulmonte. The CDC paper-bag directive suggests discarding a disposable N95 mask after five uses. But that guideline was meant for workers in a healthcare setting. For everybody else, that may not be necessary. A mask is still wearable if its elastic bands continue to create a secure fit and the material looks clean and provides good airflow. (Dust, pollen, air pollutants, makeup, skin oils, and, yes, inactivated virus eventually accumulate and clog up the filter.)

Also think about where you’ve worn the mask and for how long. Someone who wears a mask in the subway every day, for example, may need to throw it out sooner than someone who wears theirs to the grocery store every once in a while. Whatever the circumstances, switch to a fresh mask if yours is dirty, thinning, damaged, or hard to breathe through, or if it no longer maintains a good seal.

Yes! Assuming replacements are readily available, Sulmonte advises throwing a mask away if you’ve been in a place where high virus exposure is expected—for instance, if you’ve been interacting with a COVID-19–positive person.

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