How to Disinfect Your Mask: A Step

Sep 23, 2023

Cities are cautiously starting to reopen in the U.S. and around the world, but social distancing and mask-wearing are likely here to stay — at least until a COVID-19 vaccine can be developed and mass produced.

With protective gear still in high demand, buying disposable face masks can be difficult, expensive, and can exacerbate shortages for medical personnel. That's why researchers at Columbia University's Lamont-Doherty Earth Observatory investigated how to safely disinfect and reuse disposable face masks. Their research — published in April and detailed in this blog post — showed that disinfecting certain kinds of N95 respirators and surgical masks by baking them at 170 degrees F did not affect most masks’ ability to filter out virus-sized particles, even over 10 cycles of disinfection in the oven.

The FDA recently announced that not all N95 masks can or should be disinfected and reused. Learn more about whether your respirator can be reused here.

It's important to follow a few key steps in order to disinfect your mask without damaging it and putting yourself at risk. We’ve laid out the steps below, with help from study coauthors Steven Chillrud and Beizhan Yan.

Illustrations by Sunghee Kim/Earth Institute

Step 1: Preheat your oven to 170 degrees F. You may think that hotter is better — not so! Hotter temperatures could melt plastic within your mask and make it less protective. Stick with 170 degrees.

Step 2: Using clean hands, place your mask into a brown paper bag. Always handle your mask by the straps only.

Step 3: Rewash your hands. Remember to lather for at least 20 seconds.

Step 4: Fold over the top of the bag. Fold it over three times. If you’re disinfecting masks from multiple people simultaneously, use a different bag for each mask, and write each person's name on their bag. This is to ensure that the mask maintains the proper fit for each person and reduces wear and tear.

Step 5: Place the brown paper bag with mask into an oven bag or pressure cooker. Any tightly sealing, oven-safe container will work. You can put multiple brown bags into the same container.

Step 6: Place sealed bag or pressure cooker into oven for 45 minutes. Make sure the oven has finished preheating before you put it in. And set a timer — overcooking your mask could ruin it. After 45 minutes, remove and let cool. Now your mask is disinfected.

Step 7: Inspect for damages. If there are no holes or tears, your mask is now safe to reuse. Before wearing your mask, look for tears or holes, and give the straps a gentle stretch to make sure they’re still strong. Discard any mask with defects.

To view a larger version of this guide that you can save and print out, click on the image below.

Well these steps may act as helpful for some but I have heard a lot of rumors that we should not use any mask again once we have used it because masks are not meant for reuse. So shouldn't we refrain from using it?

sadly that's not an option for everyone, and disinfecting is better than nothing

I am the librarian for a community band. A lot of our music is distributed to the members. Is this method of disinfection suitable for paper sheet music?

Does this method work for KN95 masks?

Yes, for some! More details in this related blog post: https://blogs.ei.columbia.edu/2020/04/21/coronavirus-disinfect-mask-home/

Why is a paper bag necessary?

To not burn the masks.

So should not we refrain using it?

Do what you feel is best for you.

*So should we not refrain from using it?And the answer is no. No reason not to use the method.

What is an "oven bag"? What is it made of?

Plastic. They are aka oven roasting bags.

I bought an UV-C sterilizing box that can sterilize 3 masks at a time, for 15 minutes each cycle. Have been using this for months and so far the masks seem to be in good shape without obvious damage to the masks and the straps.Anybody tried the same method successfully?

Can you disinfect 3 masks in one bag?

This should read .. How to start a fire in your house.

Can you disinfect 3 masks in one bag?