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As long as the COVID-19 pandemic has not ended, mask is a mandatory item that must always be worn and carried. However, a recent YouGov poll revealed that 15 percent of Brits wear the same masks several times and do not wash them, even though they are reusable. Similarly, many people who use disposable masks do not immediately throw them away but rewearing them.
If you were to swab your used mask and grow the microorganisms in a petri dish, you would find a variety of bacteria, viruses and fungi.
“Most are likely to be harmless – you would get something similar if you sampled your hands, nose, mouth or many other parts of your body,” says Prof Cath Noakes, an expert in airborne disease transmission at the University of Leeds. However, combined with the friction and humidity associated with prolonged mask-wearing, this microbial menagerie could trigger “maskne” or mask acne.
What is maskne?
This is a general term coined to cover all manner of facial rashes associated with mask-wearing, including acne, says Dr Thivi Maruthappu, a consultant dermatologist at Highgate hospital and spokesperson for the British Skin Foundation.
“As masks can be a vector for bacteria, fungi and viruses, I would recommend washing your mask on a daily basis if you’re wearing it every day.” Soft fabrics such as cotton are less likely to cause friction than synthetic fibres like polyester, she adds.
What’s the risk of catching COVID-19 from a dirty mask?
If you had COVID-19, then your face covering would be heavily contaminated with coronavirus, as well as other diseases. Your mask would pose a risk to others if they handled it, so you should never share masks or touch someone else’s without thoroughly washing your hands.
Other people’s exhalations are a different matter. A 2019 study of healthcare workers identified various respiratory viruses on the outside of their masks, including influenza and adenovirus, a cause of the common cold. Although there is currently no data proving that such external contamination increases COVID -19 risk, “it theoretically could if you touched the mask and then touched your nose or eyes,” says Noakes.
So how often should we wash reusable fabric masks?
Ideally, after each time you wear it. “It is possible to get a mask contaminated after daily wear,” says Prof Raina MacIntyre, an infectious disease researcher at the University of New South Wales in Sydney. “We tested this and found virus on the inside and outside of masks, both surgical and cloth.”
Frequent washing is particularly important if you’re coming into contact with vulnerable individuals, says Prof William Ristenpart, a chemical engineer at the University of California, Davis. He recently discovered that the influenza virus could travel on contaminated dust particles, released by rubbing a contaminated tissue, say. In a separate study, he showed that dust was ejected from fabric masks during normal wear:
“You can imagine if someone is infected and they are wearing a cotton fabric mask that is heavily contaminated, it’s possible that those particles could carry the virus,” he says. “Of course, you can’t wash it every 20 minutes, but every five or six days is way too long.”
What if I only wear my mask for a moment, put it in my bag, then pull it out again later, or the next day?
“If done carefully and safely it should be OK,” says MacIntyre. “You must sanitise your hands first, remove the mask by touching only the straps or ear loops, and put it in a ziplock bag. It can be put on again after sanitising the hands and again, not touching the face piece.”
The more times you handle your face covering without washing it or replacing it, the greater the risk will be.
Could I spray my mask with alcohol or disinfectant instead of washing it?
Sensible as this might sound, you would then risk inhaling chemicals from the disinfectant spray. “Also, remember that washing it is not just to remove any coronavirus, it is also to remove all the other microbes, sweat and snot from your mask,” says Noakes. “A spray will not do this: just like your shirt, you need to wash your mask.”