Soon after mask awareness became a unanimous agreement among medical professionals, a debate emerged with respect to theirapplication and quality. With COVID-19 cases on the rise again across various US counties, countermeasures have reentered public ambivalence.
Initially, N95 respirators, K95, and double-layer cotton masks were praised for their ability to block large and small viral particles with comparable effectiveness. In the time since this consensus formed, it has been solidified by clinical data.
In order to receive a US safety certification, a mask needs to be able to block 95% of viral particles dispelled from an infected subject. All three masks indexed above meet this criterion baring instances of counterfeit manufacturing and mispractice.
A new study published in the BMJ Open journal lengthens the research with considerations for populations of limited means.
In their estimation, unless cloth and surgical masks are washed in accordance with guidelines established by The World Health Organization, wearers are significantly more vulnerable to infection after single-use.
“The WHO recommends machine washing masks with hot water at 60 degrees Celsius and laundry detergent, and the results of our analysis support this recommendation,” the authors wrote of their findings. “Washing machines often have a default temperature of 40 degrees or 60 degrees, 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.”
N95 Respirators, surgical masks, and face mask contamination
Cloth and surgical masks have become exceedingly popular because of their prevalence and price. However, data on their utility has been inconsistent in the past.
To date, there is only one randomized controlled trial assessing the risk associated with repeated use of a cloth face covering.
That paper (authored by the same researchers behind the new one) centered around influenza, rhinoviruses, and seasonal coronaviruses and their impact on high-risk members of health care systems.
The following results were echoed by further analysis:
–Cloth masks that were hand-washed after single-use failed to meet US health standards.
–Healthcare workers who self-washed their masks by hand doubled their risk of infection compared to those who used the hospital laundry.
-The majority of people featured in the trial were under the assumption that handwashing their cloth mask after use offered the same protection as a fresh uncontaminated cloth mask
According to the authors of the new paper, protection from viral debris is greatly diminished if cloth maks are not disinfected after a single use with warm water.
“Both cloth masks and surgical masks should be considered ‘contaminated’ after use,” Professor Raina MacIntyre, who is the first author explained in a university release. “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 that this increases the risk of contamination.
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.”
N95 masks that are properly constructed are the best options for prolonged exposure but any masks are better than none. And to that point, properly washed cloth masks and fresh surgical masks get the job done much more often than they do not.
Of course, communities who are frequently exposed to the novel coronavirus need to take as many precautions as possible.
“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. We found that if cloth masks were washed in the hospital laundry, they were as effective as a surgical mask,” the authors concluded.