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How to Sanitize KN95 Masks for Reuse

There are some scientifically methods of sanitizing your KN95 face mask that have shown efficacy in extending the use of your KN95 face mask.  These methods work at varying degrees.  If you expose a used or potentially contaminated KN95 face mask to vaporized hydrogen peroxide or ultraviolet (UV) light, results seem to show that they eliminate the SARS-CoV-2 virus from the material and preserve the integrity of the masks for up to 3 additional uses.  Interestingly enough, dry heat (70° C) was also found to eliminate the virus on masks but was effective for two uses instead of three.

Four Methods Tested

A study compared four methods for decontaminating masks which are designed for one-time use.  The methods were the following:

  • UV Radiation (260 – 285 nm)
  • 70° C Dry Heat
  • 70% Ethanol Spray
  • Vaporized Hydrogen Peroxide (VHP)

For each method, researchers compared the rate at which SARS-CoV-2 is inactivated on N95 filter fabric to that on stainless steel.

All four methods eliminated detectable SARS-CoV-2 virus from the fabric test samples, though the time needed for decontamination varied. Vaporized Hydrogen Peroxide (VHP) was the quickest, requiring 10 minutes. Dry heat and UV light each required approximately 60 minutes. Ethanol required an intermediate amount of time.

To test durability over three uses, the researchers treated intact, clean masks with the same decontamination method and assessed function via quantitative fit testing.

UV light has been used for years to decontaminate rooms, she said. She also said that so far, supplies of hydrogen peroxide are adequate.

For additional information, please review a study at the National Institutes of Health (NIH) study showing this as the result.

NOTE:  The only way to be 100% sure is to discard your used mask and use a new unused mask, however, studies do show that there are effective ways 

The study was supported by the National Institutes of Health; the Defense Advanced Research Projects Agency; the University of California, Los Angeles; the US National Science Foundation; and the US Department of Defense.

Robert Fischer, PhD, with the National Institute of Allergy and Infectious Diseases in Hamilton, Montana, and colleagues posted the findings on a preprint server on April 15. The paper has not yet been peer reviewed.

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