State of the Planet

News from the Columbia Climate School

How to Disinfect Your Mask: A Step-by-Step Guide

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

How to disinfect your mask: a step-by-step guide

step 1 preheat oven to 170 degrees fahrenheit
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
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
Step 3: Rewash your hands. Remember to lather for at least 20 seconds.
Step 4: Fold over the top of the bag
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
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
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.
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.

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Rubal
3 years ago

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?

Italia Gorski
Italia Gorski
Reply to  Rubal
3 years ago

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

JOHN HAIKIN
JOHN HAIKIN
3 years ago

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?

Ann
Ann
3 years ago

Does this method work for KN95 masks?

Jane
Jane
3 years ago

Why is a paper bag necessary?

Page Turner
Page Turner
Reply to  Jane
2 years ago

To not burn the masks.

RUBAL
RUBAL
2 years ago

So should not we refrain using it?

Renn Thomas
Renn Thomas
Reply to  RUBAL
2 years ago

Do what you feel is best for you.

Page Turner
Page Turner
Reply to  RUBAL
2 years ago

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

TP Crep
TP Crep
2 years ago

What is an “oven bag”? What is it made of?

Thegoose
Thegoose
Reply to  TP Crep
2 years ago

Plastic. They are aka oven roasting bags.

Zorro
Zorro
2 years ago

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?

Mia Bucey
Mia Bucey
2 years ago

Can you disinfect 3 masks in one bag?

frank
frank
2 years ago

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

clinicas de recuperação
Reply to  frank
1 year ago

Can you disinfect 3 masks in one bag?