Guidance on how often can you safely reuse your KN95 or N95 mask

“In the ideal world — or pre-pandemic — many masks were really viewed as single-use,” said Michael G. Knight, an assistant professor of medicine at George Washington University. “The reality is they do have a little bit more length in the amount of time we can use them.”

What’s crucial, Knight said, is making sure the mask has “maintained its integrity.” Think about how many times you’ve used it and for how long, he said.

“If I’m just putting a mask on to go to the grocery store for 45 minutes and I’m taking it off, that mask very well should be able to last me a couple of days,” he said.

But if you’re wearing a mask all day, such as during a long work shift where you may be sweating and talking all day to the point the mask becomes soiled, “then that may not be a mask that I can reuse.”

Some experts suggest having a few masks on hand so you can rotate between them. That way, after wearing one mask, you can set it aside for a few days before picking it up again, said Richard M. Carpiano, a public health scientist and sociologist at the University of California in Riverside.  ...