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N95 Masks Can Be Sterilized Up to Three Times, NIH Study Finds (1)

April 15, 2020, 6:35 PMUpdated: April 15, 2020, 7:42 PM

Health-care workers can safely reuse their N95 masks up to three times if they decontaminate them with a hydrogen peroxide-based sterilizer, early NIH findings show.

The findings released Wednesday come as the Food and Drug Administration has granted emergency use authorizations to STERIS Corp., Battelle Memorial Institute, and Advanced Sterilization Products Inc. to use their sterilization systems for N95 masks, which are typically designed for one-time use. All the companies authorized by the FDA to sterilize N95 masks use the vaporized hydrogen peroxide method, which the NIH scientists ultimately recommended, according to authorization letters the FDA sent to the companies.

FDA Commissioner Steve Hahn called these decontamination devices a “game changer” to address N95 shortages.

The Covid-19 pandemic has generated a worldwide shortage of personalized protective equipment, including N95 masks that health-care workers need to protect themselves from airborne particles and from liquid contaminating the face. Even as the Centers for Disease Control and Prevention changed its guidelines to recommend the general public wear masks, it said N95 and surgical masks must be saved for health-care workers and first responders.

Scientists at Rocky Mountain Laboratories, in collaboration from the University of California, Los Angeles, have made the study available as a paper on a pre-print server, a term used when research is part of the scientific record but hasn’t been vetted through the formal peer review process. Rocky Mountain Laboratories in Hamilton, Mont., is part of the NIH’s National Institute of Allergy and Infectious Diseases.

Researchers tested four types of decontamination methods to evaluate whether they would eliminate the SARS-CoV-2 coronavirus from the filter fabric, without damaging the fit and seal of the fabric.

All four methods eliminated any detectable levels of the virus, but only one method—known as vaporized hydrogen peroxide—experienced no failures when research volunteers wore the decontaminated masks.

This method uses a low temperature hydrogen peroxide vapor that fills the sterilization chamber, penetrates the device, and sterilizes exposed surfaces.

Other methods, such as ethanol spray, damaged the integrity of the respirator’s fit and seal after two decontamination sessions.
Respirators treated with UV and dry heat procedures began showing fit and seal problems after three decontaminations.

The researchers said this indicated UV and heat treatment could potentially allow for the respirators to be used twice, but vaporized hydrogen peroxide was the most effective method. It could sterilize masks after a 10-minute treatment, whereas UV and dry heat take about an hour.

(Updated throughout with additional reporting.)

To contact the reporter on this story: Jeannie Baumann in Washington at jbaumann@bloomberglaw.com

To contact the editors responsible for this story: Fawn Johnson at fjohnson@bloomberglaw.com; Peggy Aulino at maulino@bloomberglaw.com

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