You’re ready to swap your old cloth masks for N95s as some experts recommend, but the higher price tag and two little words — “single use” — are giving you pause. How long can you really wear an N95 and still protect yourself and others from Covid-19 risk?

“I wear mine for a week,” said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech.

An N95 mask’s material and filtration ability aren’t “going to degrade unless you physically rub it or poke holes in it,” Marr said. “You’d have to be in really polluted air … for several days before it lost its ability to filter out particles. So, you can really wear them for a long time.

“People have been talking about 40 hours — I think that’s fine. Really, it’s going to get gross from your face or the straps will get too loose or maybe break before you’re going to lose filtration ability,” she added.

The reason why N95 masks are designated as single use is because they’re categorized as medical masks, said Erin Bromage, an associate professor of biology at the University of Massachusetts Dartmouth.

In medical settings, health care workers change masks more frequently to avoid “cross-contaminating a patient room with equipment that was worn in a room of an infectious person and then moving to the next room and bringing that infection with you,” he said. “When you then take a medical-grade thing that’s single-use and put it in the general public, we’re not worried about you cross-contaminating different environments you’re being in. It’s really about providing protection to you.”

N95s “used to be only $1 or so each,” Bromage added, but prices have recently spiked as public demand for these masks has increased amid Omicron variant concerns. If you safely reuse N95s, you’re getting at least two or three days of use from one mask, Bromage added, but “I realize that it still adds up to an expense.”
Some local public health departments, such as the Maryland and Milwaukee health departments, are offering free N95 masks.