It depends, but you should be able to use N95s and KN95s a few times. The U.S. Centers of Disease Control and Prevention says health care workers can wear an N95 mask up to five times. But experts say how often the average person can safely wear one will vary depending on how it’s used. Using the same mask to run to the grocery store, for example, is very different than wearing it all day at work.
The amount of time a mask is worn is more important than how frequently it’s worn, says Richard Flagan, who studies masks and aerosols at the California Institute of Technology. In general, he recommends limiting the use of an N95 mask to about two or three days.
With every breath you take in an N95, particles accumulate on the mask, Flagan says. That could make it more difficult to breathe if the mask has trapped a lot of particles.
