MONDAY, Oct. 5, 2020 (HealthDay News) — The homemade cloth masks recommended for slowing the spread of COVID-19 seem to expel invisible cotton fibers into the air as people talk, cough or even breathe — underscoring the importance of regularly washing them, researchers say.
In experiments, researchers found that medical-grade masks — surgical and N95 — blocked most exhaled “particles” from the wearer’s mouth. But the results with cloth masks, fashioned from T-shirt material, were surprising.
People actually emitted more invisible particles while wearing a cloth mask than with no mask at all. And that, researchers said, was because the masks released microscopic cotton fibers.
There’s no proof at this point that the fibers can carry infectious viral particles. And experts stressed that everyone should keep wearing masks according to public health guidance.
“They didn’t show that infectious particles are being released,” said Ravina Kullar, a spokesperson for the Infectious Diseases Society of America. “So it’s not clear what this means from an infectious disease standpoint.”
And certainly, she added, people would put themselves at greater risk of contracting SARS-CoV-2 if they went out in public mask-free.
William Ristenpart, the senior researcher on the work, agreed that no one should take the findings as an argument against mask-wearing.
“That’s not what we’re saying at all,” said Ristenpart, a professor of chemical engineering at the University of California, Davis.
Instead, he thinks the practical message is this: Wash your mask after each wearing. If tiny cotton fibers are released into the air, let them be as clean as possible.
The U.S. Centers for Disease Control and Prevention and other health authorities urge the people to wear a cloth mask when they are out in public, especially in places where it is hard to maintain physical distance from others.
The CDC recommends wearing masks with at least two layers of fabric, and says “simple masks can be made at home with washable, breathable fabric.”
It’s not clear, however, exactly how well such homemade masks work. No one is going to run a clinical trial where people are randomly assigned to either wear masks or walk around mask-free.