Wearing a mask has been the norm for nearly two years now, beginning shortly after the COVID-19 pandemic. And while they’ve been proving to help in preventing the spread of disease, sometimes wearing the same mask every day too often can actually do the opposite. Because of this reason, if you have a reusable mask, it’s important to sanitize them before you use them again.

“The concern about wearing a mask in public, obviously, if you get particles on it, perhaps even the virus, but if you store it in a dry bag, you are essentially sanitizing again over a period of time,” said Dr. Joe Gastaldo, Infectious Disease Expert at OhioHealth.

The good news: Sanitizing your mask is actually really easy. All you need is a brown paper bag!

Yes, you read that right. Just a bag—no fancy cleaning products or laundry detergent. Experts suggest simply keeping your mask in a brown paper bag for about 24-48 hours in dry area. This can extend its life and make it safer to wear out in public once again.

So what’s the magic here? It’s actually not so much about the bag itself, as it is not using the mask for a period of time, experts explain.

“It’s not the bag that’s doing the magic trick, it’s actually the process of keeping the mask away from decontaminating someone else or a surface, and also keeping a dry environment in order for the virus to not spread or stay on the mask,” explained Dr. Jessica Shepherd, Chief Medical Officer at VeryWell Health in New York.

The bag trick works best on high-quality masks, such as KN95 or N95, aka the holy grail of masks, which filter out the most virus particles.

“You really want to think about having the highest quality of mask as possible,” said Dr. Gastaldo. “When it comes to how a mask performs the ones that perform the best in public filter up to 95% of particles at 0.3 microns. And in that regard, you have to use an N95 mask but I think what’s more available for the public are KN95 masks.”

If you don’t have access to masks like these, any mask will do. “The thing really is making sure that you can have access to a mask period,” said Dr. Shepherd. “But if you do have the ability to choose between a cloth and an N95, the better option is going to be N95.”

Have you ever tried sanitizing your mask this way?