Here's the best way to clean your face mask

Whether you’re wearing a disposable surgical mask or a cloth bandana, here’s how to make sure your protective gear stays sanitary.

Published 1 Jun 2020, 13:50 BST, Updated 5 Nov 2020, 04:57 GMT
Photograph by Bobby Doherty, National Geographic

Wearing a mask in public once meant you were dressed for Halloween, or to rob a bank. Yet in a few short months, because of COVID-19, this clothing item has evolved into everyday wear.

The World Health Organisation recommends wearing a surgical mask—the type found in hospitals—if you feel ill or are caring for a sick person. The U.S. Centres for Disease Control and Prevention go further and advise a cloth covering for anyone venturing into a crowded public place. Some people are exceeding those official guidelines and also wearing reusable or disposable gloves in public.

Experts warn, however, that misusing any of this protective gear could potentially expose you to just as many germs as you would contact without it—because the masks and gloves themselves collect viruses if they’re not cleaned or changed frequently, and because they may then contaminate your hands or things that you later touch without protection.

“When I see someone [wearing gloves] touching countertops and then digging in their purse, I think, Now they’ve created cross contamination and voided whatever protection they’re wearing,” says Jade Flinn, a nurse educator in the biocontainment unit at Johns Hopkins University in Baltimore, Maryland.

Social distancing and frequent handwashing remain the most valuable ways, experts say, to keep from spreading or being infected by SARS-CoV-2, the virus behind the global pandemic.

But if you do venture out wearing masks and gloves, here’s how to clean them, when to dispose of them, and why you ultimately shouldn’t fear harbouring the virus on the rest of your clothes.

How to clean a cloth mask

A standard laundry cycle is enough to wash the coronavirus off cloth, according to the WHO and CDC.

“Because it’s an enveloped virus, it’s really susceptible to detergents,” says Rachel Graham, a virologist at the University of North Carolina at Chapel Hill. The envelope that encapsulates viruses like influenza and SARS-CoV-2 is a delicate layer of oily lipids and proteins, held together by surface tension.

Laundry detergents and soaps contain surfactants, chemicals that easily break that envelope apart by reducing surface tension, explains Joshua Santarpia, a pathologist at the University of Nebraska Medical Centre in Omaha. A surfactant molecule has one end that’s attracted to oil and grease, while the other is attracted to water. The oil-loving end wedges into the coronavirus’s envelope, busting it apart. The remnants get trapped in circular pods of surfactant called micelles and are washed away in water.

“The interaction of that surfactant with the viral envelope pretty quickly destroys the ability of that virus to be infective,” Santarpia says. Potent surfactants are found in most home and commercial cleaning products.

The water temperature in the washing machine doesn’t matter as long as you use detergent. “The masks made of cotton withstand higher temperatures, so if it makes you feel better to wash it at a higher temp, go ahead and do that,” Graham says. The high, concentrated heat from a dryer offers added protection: it’s enough to kill most microorganisms.

The CDC provides step-by-step instructions for removing gloves and advises you to wash your hands after doing so.

Photograph by Photo Illustration by Bobby Doherty, National Geographic

What if I’m wearing a surgical or N95/FFP2 mask?

Unlike cloth coverings, medical masks intended for single use are made of non-woven synthetic fabrics that can’t withstand a typical laundry cycle.

“If you wash them it will do a lot of damage to their filtration capability,” Santarpia says. Out of necessity, healthcare workers have been reusing N95 respirators—the dome-shaped, tight-fitting masks that are the only verified way to efficiently filter small particles like viruses. The facilities where Flinn and Santarpia work use hospital-grade disinfectants that preserve the mask’s integrity through the cleaning process.

Santarpia’s Nebraska hospital is also sanitising masks with UV-C, a high-energy type of ultraviolet light. That allows staff to re-wear masks a handful of times, Santarpia says. Because UV-C is considered more intense and more likely to cause cancer than UV-A and UV-B, this brand of sterilisation should only be conducted under expert supervision by people trained in using UV-C light, according to the CDC.

For the general public, the bottom line is, you should ideally only wear medical masks once—and if you’re going to reuse them, set them aside between uses long enough for the virus to decay.

How long is that? Scientists are still unpacking exactly how long SARS-CoV-2 lasts on surfaces, in the air, and on masks. Preliminary evidence released late last month without peer-review found traces of the coronavirus persisted for considerable time on N95 respirators.

“The take-home message is that the virus can remain infectious for several hours, potentially up to a few days, on various surfaces, including masks,” says Amandine Gamble, one of the study’s authors and an infectious disease expert at the University of California Los Angeles. She suspects the coronavirus gets trapped within a mask’s fibres, which poses a hazard until the germ spontaneously degrades over time. For this reason, the CDC advises against wearing an N95 respirator for more than 8 hours total, and unless otherwise specified by the manufacturer, those face filters should be discarded after five reuses. Similar precautions should be extended to FFP2/FFP3 respirators according to manufacturer instructions. 

But even outside of hospitals, respirators that are reused repeatedly in public could collect virus over time and increase the wearer’s own chances of accidental exposure.

“The one important thing to keep in mind is that the probability of getting infected increases with the number of viral particles encountered,” she says. “It is not an on-off process, but a gradual one.”

Can you reuse and wash your gloves?

Public health organisations do not recommend wearing gloves of any kind to prevent contracting the coronavirus.

“As long as your skin is intact, it’s a very effective immune barrier,” says Graham, adding there’s also no evidence the coronavirus can squeeze through a cut and it doesn’t circulate well in the bloodstream.

However, if your worries override your desires to follow health guidelines and you feel the need for the extra layer of protection, be as careful as you would with ungloved hands. Limit the number of things you touch, and—as always—don’t touch your face.

“My concern is some people think they are protected” by gloves, says Jane Greatorex, a virologist at Cambridge University in the U.K. Gloves “need disposing of or washing in the same way you would your hands.”

The CDC provides step-by-step instructions for removing gloves and advises you to wash your hands after doing so.

“Single-use gloves aren’t really meant to be washed, and you’re much more likely to get a breach in your gloves,” says Santarpia. “People should focus much more on hand hygiene than glove wear.”

What about everything else I’m wearing?

Going to the grocery store doesn’t mean you have to throw away your clothes. That’s because enveloped viruses like the coronavirus don’t easily survive on porous surfaces such as cotton shirts, polyester blouses, and denim jeans.

Coronaviruses primarily spread in respiratory droplets, which are mostly water and keep the virus moist until it can reach another body. Given time—anywhere from a few days to a week—the viruses will decay by simply drying out, says Gerardo Lopez, a University of Arizona environmental microbiologist who has studied how viruses transmit from various surfaces.

With a germ that spreads as easily SARS-CoV-2, he says, it’s important to frequently clean anything—hands, masks, doorknobs, phones—that receives regular human contact. “Don’t underestimate the possibility of a virus staying on something,” Lopez adds.

But your regular clothes aren’t what you should worry about. When respiratory droplets land on a textile such as cotton, it absorbs some of the moisture, drying out the droplets and exposing the virus particles and their fragile envelopes to the air.

“The lipid layer on the outside is going to dry up, and the protein it needs to attach to receptors become inoperable,” says Lopez. The virus’s genetic material might be left behind, “but it's no longer really viable,” he adds. And your washing machine will take care of it.

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