As the pandemic has evolved, so have mask requirements. While cloth masks were considered acceptable in the early days of COVID-19, the transmissibility of Omicron has forced health officials to rethink the effectiveness of those face coverings—and urge people to use surgical masks, as well as KN95 and N95 masks.

The supply shortages that we saw in 2020 have largely been resolved now, but disposable masks can’t just be tossed in the washing machine after they’re used, which increases household expenses when inflation is soaring.

While the official recommendation for these masks is a single use, health officials say that can be stretched, though you will have to observe some limitations.

Here’s what you need to know:

Can you reuse N95 and KN95 masks?

You can—several times, in fact. The CDC recommends using an N95 or KN95 mask no more than five times in general, though it does acknowledge that some models can be worn even more.

Some doctors recommend rotating several masks, letting each sit for a day or two before reusing it.

Where should I store my mask when I’m not wearing it?

Believe it or not, a breathable paper bag could be the best place. That’s the recommendation of the CDC. Health care workers were advised to wait a minimum of five days before reusing their N95, though health officials now urge them to wear new masks since they’re available. The exposure levels of a health care official and someone who has made a trip to Walmart and the grocery store are vastly different, though, and the average person likely won’t need to wait that long between uses.

It’s also a good idea to store them in a warm area, as heat has shown promise in decontaminating certain models of face coverings. In 2020, the Department of Homeland Security even offered some tips on using your Instant Pot to decontaminate certain masks.

What are signs I should replace my mask?

It all comes down to the fit of the mask and the seal it creates on your face. Every time you put a mask on or take it off, the straps can stretch. If you start to see signs of that, it’s time to discard it. Similarly, if you see deterioration on the mask, you’ll need to get rid of it.

Also, if you accidentally touch the inside of the mask, toss it. Masks should only be handled by the earloops.

Can I wash my N95 or KN95 mask?

No. Even though they’re triple layered, submerging these masks in water reduces their effectiveness.

What’s the difference between KN95 and N95 masks?

N95 masks are the pinnacle of the face covering world. They’re the ones used by medical professionals who are on the front line of COVID, as they’re especially effective in blocking airborne viruses, filtering out at least 95% of very small particles.

KN95 masks are largely imported from China and aren’t approved for use in medical settings, since they’re not regulated by U.S. officials. But a well-fitted KN95 is still more effective in stopping the virus than a cloth or disposable surgical mask.