Catherine Clase, a nephrologist and associate professor of medicine at McMaster University, tells Verywell that in terms of which face mask hygiene practices are most effective, the evidence is lacking.
That said, there are a few things we do know about keeping face masks clean.
When to Wash Your Mask
Before you ask how to wash your mask, you’ll probably want to know how often you should wash it. Clase says that reusable face masks need to be washed every day.
“If you have a mask that you use for very low-risk activities—like the one you keep by your front door for a brief, distanced, encounters, and you always hand sanitize after putting it on and taking it off—you could wash it less often," she says. “Be sure that you know which side is which, which mask is your own, and hang it so that it doesn’t contaminate other things.”
If you are wearing a mask continuously for several hours, you might need a second mask to get through the day because of the moisture build-up.
Raina MacIntyre, PhD, an epidemiologist at the University of New South Wales, agrees that people should wash their reusable face masks daily.
How to Wash Your Mask
No specific data exists on whether it’s better to toss your mask in the washing machine or hand-wash it. What’s more important is the water temperature.
“Health Canada specifically suggests a hot cycle whereas the CDC says the warmest appropriate water setting for the cloth and for the mask,” MacIntyre says. Health Canada also recognizes hand-washing masks with soap and warm or hot water as a possible method for cleaning your face mask.
“In general, we would expect there will be a lower amount of virus surviving at higher temperatures, with longer exposure times—time in the wash—and with higher concentrations of soap and detergents,” MacIntyre says. “But we don’t have good specific information on this for SARS-CoV-2 at present.”
Still, we have some information. MacIntyre conducted a study published in the BMJ that found healthcare workers in Vietnam who hand-washed their face masks had double the risk of getting infected with respiratory viruses than the workers whose masks were cleaned in the hospital laundry.
MacIntyre points out that the main problem with hand-washing your mask is that the exposure time (how long it’s in contact with the water and detergent) is shorter than it would be if you put it in the washing machine.
While a washing machine cycle might be more effective than hand-washing because it offers longer exposure, Clase says that if hand-washing is combined with a hot soak with detergent or bleach, it could be as effective.
“We don’t know what the threshold is; it’s possible that virus might be inactivated in minutes in warm soapy water," Clase says. “But in the absence of direct evidence, recommendations are framed to be as safe as possible.”
It would make sense that the heat of a tumble dryer would inactivate the virus, but it’s not known whether this is needed after a good wash. While both Health Canada and the CDC stress the importance of thorough drying, neither specifies a method.
The World Health Organization (WHO) recommends washing face masks in water that is at least 60 degrees Celsius (140 degrees Fahrenheit). While a washing machine can reach that temperature, you’re not likely to get there with your sink. “These high temperatures cannot be achieved with hand-washing—you would burn your hands,” MacIntyre says.
Mask Material Matters
Clase also notes that the material of your mask matters when you’re thinking about how to wash it, just as it matters for clothes. “Some masks incorporate fine fabrics such as chiffon and silk which may be quite altered by a hot wash," she says.
Clase recommends two- to four-layered cotton masks. Based on her review of evidence published in Mayo Clinic Proceedings, Clase believes that a mask with at least 100 threads per inch [TPI] is adequate.
Other research indicates cotton with a high thread count may not be breathable, while another study found that three of the five best performing materials included woven cotton with high to moderate thread counts.
“Other materials, including synthetics, may also work well, but we have less information on them at the moment," Clase says. “And when we are thinking about washing, the advantage of cotton is that they can be washed hot and in a machine.
You might have heard that you can use UV-C light to clean a face mask, but Clase says that it’s not a recommended method by either Health Canada or the CDC for cloth masks. However, UV-C light has been shown to work on N95s. MacIntyre says masks that cannot be washed are ideal for UV-C cleaning.
The Right (and Wrong) Way to Wear a Mask
A survey of 1,009 people conducted in September by Signs.com found that 24.5% of people admitted to sharing their face mask with someone else (Gen Xers were the most likely age group to share masks). For people who wear disposable masks, 40.8% admitted to trying to wash it, while 44.2% admit they have worn a disposable mask multiple times.
Clase says one thing that many of us are doing wrong is touching our faces while we wear our masks—something we often do without realizing it. When you touch your face or mask, it increases the risk of cross-contamination.
“It’s very hard for us not to touch our faces frequently,” Clase says. “With practice and effort, we can improve. If you realize you’ve touched your face or mask, wash your hands,” she says.
The other challenge for mask-wearers is trying to figure out what you should do with it in the moments when you don’t need it. “Wearing it under your chin, off one ear, or on the forehead, all create the risk of contaminating your nose and mouth with the outer surfaces," Clase says.
Ideally, take your mask off and put it in a paper bag before you pop it into your purse or pocket. It’s also important to wash your hands before you put your mask on and after you take it off.
“The best solution is probably what we do in health care—just keep it on, even if you are briefly in an area where you don’t need it, rather than putting it on and taking it off repeatedly," Clase says.
MacIntyre adds that handling your mask by touching the facepiece, wearing it over your mouth but not covering your nose, and wearing a mask under your chin are also ways to cross-contaminate or transmit viruses.
When Can You Take Your Mask Off?
Clase says that when you’re running errands, it’s okay to remove your mask and put it back on while you’re driving. “Most of these errands will be each quite low-risk,” she says. “Put the mask on with the same side towards you each time. Store it in a paper bag between uses.”
If there is a high-risk use, such as visiting someone in a long-term care facility or you were near someone sneezing or coughing, it’s probably better to use a new mask.
As for driving with a mask, that’s safe as long as it’s not impairing your vision. You can adjust the fit of your mask by wearing the ear loops on adjustable “ear savers,” or by using small beads or elastic bands to change their size.
The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.
It can help to store some extra masks—reusable, disposable, or both—in your car or bag in case the one you’re wearing gets contaminated and you aren’t able to properly clean it.
