By Sarah Fecht
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.