Face coverings should be washed every day to help stem the spread of the coronavirus, scientists have stressed.
Throughout the UK, wearing the personal protective equipment is enforced in many public spaces, including trains, shops and cinemas.
While donning a face covering may be our “new normal”, re-useable options could encourage people to wear the makeshift mask for days on end, without being washed in-between.
To better understand the impact of this, scientists from the University of New South Wales in Sydney analysed a 2015 study that looked at how cloth face coverings prevented respiratory viral infections among healthcare workers.
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While the coronavirus was not studied specifically, results revealed those who hand washed their masks every day were more than twice as likely to catch a common cold virus than the workers who used the hospital laundry.
Amid the coronavirus outbreak, the scientists have stressed people should “take every precaution”, adding a daily 60C (140F) wash for face coverings is “essential for safety”.
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During the pandemic, Britons are being urged to wear face coverings due to them generally being more comfortable than medical masks, which should aid adherence.
“Both cloth masks and surgical masks should be considered ‘contaminated’ after use,” said the study’s lead author Professor Raina MacIntyre.
“Unlike surgical masks, which are disposed of after use, cloth masks are re-used.
“While it can be tempting to use the same mask for multiple days in a row, or to give it a quick hand wash or wipe over, our research suggests this increases the risk of contamination.”
Television adverts, bus stop posters and train station tannoys remind people of the importance of wearing face coverings.
When it comes to washing them, however, the guidance is rather less straightforward.
Northampton General Hospital NHS Trust put together a graphic stating coverings should be “washed properly after use”, defined as “in a washing machine using normal detergent and with your regular laundry at the warmest appropriate setting”.
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Northern Devon Healthcare NHS Trust advises staff, patients and visitors wash any covering every day “ideally at 60C” – advice that is echoed by the World Health Organization (WHO).
The US Centers for Disease Control and Prevention, however, states coverings should be washed “regularly” at “the warmest appropriate water setting for the cloth used to make the mask”. It also gives advice on how to clean coverings by hand.
To better understand the importance of correctly washing face coverings, the Sydney scientists analysed a study carried out in Vietnam in 2011, but published in 2015.
Cloth and medical masks were compared among more than 600 healthcare workers in “high risk wards” across 18 hospitals.
“Given the potential implications for health workers or community members who are using cloth masks during the pandemic, we did a deep dive into the 2011 data on whether the health workers in our study washed their masks daily, and if so, how they washed their masks,” said Professor MacIntyre.
The rhinovirus, which causes the common cold, was found on both the medical and cloth masks.
Results – published in the journal BMJ Open – revealed the risk of infection was more than double among those who hand washed their masks every day, compared to the workers who made use of the hospital laundry service.
“We found if cloth masks were washed in the hospital laundry, they were as effective as a surgical mask,” said Professor MacIntyre.
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“While someone from the general public wearing a cloth mask is unlikely to come into contact with the same amount of pathogens as healthcare workers in a high risk ward, we would still recommended daily washing of cloth masks in the community.
“COVID-19 [the disease caused by the coronavirus] is a highly infectious virus, and there is still a lot we don’t know about it, and so it’s important we take every precaution we can to protect against it and ensure masks are effective.”
The scientists concluded: “Daily washing of cloth masks at the recommended temperature of 60C–90C (194F) in whatever setting they are used, including the community, is essential for safety.”
Professor MacIntyre added: “The WHO recommends machine washing masks with hot water at 60C and laundry detergent, and the results of our analysis support this recommendation.
“Washing machines often have a default temperature of 40C (104F) or 60C, so do check the setting.
“At these very hot temperatures, hand washing is not possible.
“The clear message from this research is cloth masks do work, but once a cloth mask has been worn, it needs to be washed properly each time before being worn again, otherwise it stops being effective.
“There is much research on the design, fabric and construction of masks, but washing is also key for protection.”