How to clean and sterilize your homemade face mask

In early April, the U.S. Centers for Disease Control and Prevention (CDC) started recommending people wear face masks in response to the COVID-19 pandemic, commonly known as the coronavirus. In order to save surgical masks and medical masks for health care workers, the CDC said the general public should use cloth face coverings made out of household items.

“That’s the most important thing to keep in mind — that the purpose of the mask is not to protect the wearer,” Dr. Dean Winslow, an infectious disease specialist at the Stanford University Medical Center, told Digital Trends. “It’s to protect others, in case [the wearer is] asymptomatic or minimally symptomatic but shedding the virus.” The masks are useful for places like the drugstore, where it may be difficult to stay six feet away from someone else.

Coughing, exhaling, and talking all release droplets into the air that can infect others. In other words, the mask isn’t protecting you from the world; it’s protecting the world from you. That’s why it’s important to wear one, even if you don’t have any symptoms. You can still spread the disease before you start coughing or if you’re infected but never get very sick. Winslow also wants to remind people that masks aren’t a substitute for more effective measures, like staying six feet away from others. “Shelter in place and social distancing are, in the big scheme of things, much, much more important than the wearing masks are, in my opinion,” he said.

how to clean your homemade mask
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How often should you clean your mask?

You’ll want to make your mask out of something that will hold up to a lot of washing. There are tutorials for making masks out of T-shirts, bandannas, and bed sheets. Some materials, like flannel and heavyweight cotton, are likely better at stopping the droplets than others. The mask is going to be covered in everything that comes out of your mouth.

While Winslow said there’s a small chance you could get some contamination on the outside of the mask when you’re outdoors, there are other reasons for regularly cleaning it. “It probably won’t smell too good by the end of the day,” he said. “You’re probably going to wash it every day.”

Soap up

The Environmental Protection Agency (EPA) has a list of antimicrobial products that have been shown to be effective at killing viruses similar to COVID-19. There are a couple options listed for presoaking laundry, but the majority are for hard, nonporous surfaces and meant to be used in hospitals, schools, and other places that typically use industrial cleaners.

hand washing
Johan Ordonez / Getty

Dr. Frankie Wood-Black, division chair of engineering, physical science, and process technology at Northern Oklahoma College, says it’s likely the detergents you have on hand will suffice for cleaning masks. “If washing my hands with warm, soapy water is going to be fine for my hands, something similar to that is going to work for my mask,” she said.

She’s concerned that people who are new to wearing masks will go through an adjustment period — literally. “When people are wearing a mask, they have to be even more conscious of not touching their face,” she said. It’s also important to carefully remove the mask when you get home, so you don’t contaminate your hands.

What temperature will kill the coronavirus? 

“I always like to make sure that consumers understand the difference between cleaning and sanitizing,” said Mindy Costello in an email to Digital Trends. She’s a product certification specialist and registered environmental health sanitarian at the National Sanitation Foundation (NSF), which inspects and certifies appliances and other products. “Cleaning is removing stains or soil from a surface or fabric. When sanitizing, you’re actually destroying microorganisms like bacteria, mold, and yeast,” she said. “If you want to reduce your risk of getting sick, sanitizing is the way to go.”

There aren’t published studies on how COVID-19 stands up to various temperatures, but the World Health Organization (WHO) found that 132.8 degrees Fahrenheit (56 degrees Celsius) is hot enough to kill the coronavirus that causes SARS. Other tests found higher temperatures, up to 149º F (65º C), are more effective.

Because those temperatures are scalding for human skin, using either warm or cold water and soap for at least 20 seconds is the CDC’s guideline for hand-washing. Since fabric can withstand higher temperatures, the CDC recommends washing clothing in the “warmest appropriate water setting.”

Why do washing machines work?

Some washing machines have allergen and sanitization settings. To qualify for an NSF certification for sanitization, washers must reduce 99.9% of microorganisms during the sanitization cycle. “The NSF International protocol does not specify a temperature for the washing machine’s sanitizing cycle to achieve,” said Costello. For the allergen certification, the washer has to remove at least 95% of house dust mite allergens and feline dander, and the water must reach 131º F (55º C). Neither certification includes testing on the efficacy of killing coronaviruses. NSF International recommends following the CDC’s guidance for laundry,” said Costello. “In some cases, the sanitizing cycle on your washing machine may be the hottest setting.”

laundromat interior
Stephanie Keith / Stringer / Getty

Even if your washer doesn’t have special sanitization settings, the mechanical action of the washer — tossing the clothes about and having them rub against each other — and the detergent will still kill the virus. It has a lipid layer that soap helps break down. (The American Chemical Society has a great video explaining more in-depth about why soap is great at destroying the COVID-19 virus.) “This is an RNA virus, so it’s not particularly hardy,” said Winslow. He agrees any warm cycle will probably do the trick. “That just dissolves the detergent more efficiently, if nothing else,” he said.  

Can you use your dishwasher to clean your mask?

Shoes, hats, toys — there’s no limit to the weird stuff people put in their dishwashers to clean. Like washing machines, some newer models have sanitization settings. The NSF also certifies this setting. “During testing, three common organisms – staphylococcus aureus, klebsiella pneumoniae, and pseudomonas aeruginosa – are added to the loads of dishes,” said Costello. “The level of bacteria is tested afterward. The water in dishwashers that earn the NSF International mark for sanitization must reach 150 degrees Fahrenheit (65.56º C) during the final rinse and stay at or above that temperature long enough to achieve the 99.999 % reduction.”

A 2000 study from the Institute of Environmental Medicine and Hospital Epidemiology found that 160º F (71º C) temperatures were adequate for disinfecting medical equipment, but not every dishwasher will get this hot. The water is still mixing with soap, which will help kill the virus, though it’s not being subjected to the same mechanical action as a washer produces. There’s also the potential that the mask could become wrapped around some of the dishwasher’s rotating parts and break the machine.

Can you boil your face mask?

For those living in homes with the bare minimum of appliances, it might be counterintuitive to risk a trip to the laundromat to wash a face mask. Winslow thinks most people will be fine just doing what they’d do if they were on a trip and forgot extra underwear: Fill the sink with hot, soapy water and hand wash. Wood-Black compares it to washing any item of clothing where there’s concern about a more familiar bacteria or virus, like salmonella or norovirus. “The same precautions are going to apply,” she said.

But if you’re symptomatic and living with others, you might want to be a little more rigorous. In that case, boiling your mask could be an option. Lots of people do this with smelly dish towels. Use a large pot and enough water to make sure it doesn’t all evaporate away. Leave the mask in the water for several minutes and swirl it around occasionally with tongs.

Taiwan’s Food and Drug Administration recently proposed a fairly novel solution to reusing surgical masks. It suggests putting one in a rice cooker, with no water, and leaving it on for three minutes. Wood-Black doesn’t think that step is necessary and is potentially dangerous. “I would not recommend putting them into a dishwasher, into a microwave, into a rice cooker, or anything like that,” she said. “Because you are more likely to create a potential hazard.” If you made a mask out of a bandanna that has a metallic thread, for example, and put it in your microwave, it could damage the appliance or start a fire.

When should I get a new mask?

Some of these cleaning methods are harder on fabrics than others. Hotter water breaks down fibers more quickly, for example. A mesh laundry bag may help protect it from some of the twisting and turning that can happen as the washer rotates. If you’re noticing holes in your mask, it’s time to replace it.

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