Last week Victoria’s face mask regulations changed to ban the use of face shields and make it mandatory for all residents over the age of 12 to wear a fitted face mask when they leave the house.
Masks are also growing in popularity in other states, but while cloth masks are still fine to wear, according to the new Victorian regulations, new research from the University of NSW’s Kirby Institute has raised concerns about how people are using them.
The Kirby Institute analysis says that cloth masks must be washed daily at high temperatures to protect against COVID-19 infection.
“Both cloth masks and surgical masks should be considered ‘contaminated’ after use,” explained Professor Raina MacIntyre, who conducted the study.
“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 handwash or wipe-over, our research suggests that this increases the risk of contamination.”
The analysis did not specifically test for SARS-CoV-2 as it relied on unpublished data from a randomised control trial published in 2015, which remains the only trial of its kind into the efficacy of cloth masks in preventing viral infections.
The analysis did, however, look at similar respiratory pathogens such as influenza, rhinoviruses (common cold) and seasonal coronaviruses and was based on self-reported washing data conducted by health workers in high risk wards.
“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,” Prof. MacIntyre said.
“We found that if cloth masks were washed in the hospital laundry, they were as effective as a surgical mask.
“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.
“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,” she said.
According to the analysis, handwashing the masks did not provide adequate protection.
Healthcare workers who self-washed their masks by hand had double the risk of infection compared to those who used the hospital laundry.
The majority of people in the randomised control trial handwashed their masks, and this may be why the cloth masks performed poorly in the original trial.
“The World Health Organization (WHO) recommends machine washing masks with hot water at 60°C and laundry detergent, and the results of our analysis support this recommendation,” said Prof. MacIntyre.
“Washing machines often have a default temperature of 40°C or 60°C, so do check the setting.
“At these very hot temperatures, handwashing is not possible.
“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.”
The original study was conducted in hospital health workers in Vietnam in 2011.
Study participants were randomly assigned to use cloth masks, surgical masks or no masks.
The researchers found that two-layered cotton cloth masks were not as effective as surgical masks in a hospital setting, and that they potentially increased the risk of infection when compared with wearing no mask at all.
“This has become a flashpoint for the debate around cloth masks between pro and anti-mask groups, both of which have focused on our 2015 study in their arguments – but a more detailed look at the washing data suggests that handwashing made the cloth masks riskier, rather than the cloth mask itself,” Prof. MacIntyre said.
“When we break the data down in this new way, comparing machine washing with handwashing, a machine-washed cloth mask is as effective as a surgical mask.
“There is much research on the design, fabric and construction of masks, but washing is also key for protection.”
Have you been wearing a mask? Do you use disposable surgical masks or cloth masks? How often have you been washing your cloth mask?
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