Cloth face masks have been proven in studies to offer a high level of protection against the novel coronavirus, but new research out of Australia is now suggesting that they must be washed at high temperatures after every use.  

If that extra step isn’t taken, the face masks can increase the risk of contamination, according to analysis from the Kirby Institute at the University of New South Wales at Sydney that was recently published in BMJ Open. 

“Both cloth masks and surgical masks should be considered ‘contaminated’ after use,” Professor Raina MacIntyre, who conducted the study, said in a news release. 

“Unlike surgical masks, which are disposed of after use, cloth masks are reused. While it can be tempting to use the same mask for multiple days in a row, or to give it a quick handwash or wipe-over, our research suggests that this increases the risk of contamination.”  

In concluding their findings, the researchers examined unpublished data from a randomized controlled trial they published in 2015 that analyzed how effective cloth face masks are in preventing viral infections.

“Given the potential implications for health workers or community members who are using cloth masks during the pandemic . . . we found that if cloth masks were washed in the hospital laundry, they were as effective as a surgical mask,” MacIntyre said.

The researchers noted that the initial study was conducted roughly five years ago, so they weren’t able to directly test the novel coronavirus. Instead, they looked at common respiratory pathogens like influenza, rhinoviruses, and seasonal coronaviruses in their analysis.

“While someone from the general public wearing a cloth mask is unlikely to come into contact with the same amount of pathogens as a healthcare worker in a high-risk ward, we would still recommend daily washing of cloth masks in the community,” MacIntyre said.

“COVID-19 is a highly infectious virus, and there is still a lot that we don’t know about it, and so it’s important that we take every precaution we can to protect against it and ensure masks are effective.”

The World Health Organization has suggested that cloth face masks or coverings should be washed with laundry detergent and water that is at least 140 degrees Fahrenheit.

“The results of our analysis support this recommendation,” MacIntyre said. “The clear message from this research is that 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.”

Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek, and Arirang TV. Follow or contact him on LinkedIn.  

Image: Reuters