Sterilization process allows for reuse of N95 masks

April 08, 2020

Update: The U.S. Food and Drug Administration has approved University Health System’s use of a hydrogen peroxide gas process to sterilize N95 face masks, so they can be worn three times instead of once. The approval followed a review of a pilot program reported in this article. 

There’s nothing like a crisis to spur innovation.

Hospitals throughout the country have reported shortages of N95 face masks, the gold standard for protecting medical staff taking care of patients who may spread COVID-19.

Even hospitals like University Hospital, not currently facing shortages of masks, have watched with concern. There’s no predicting how many symptomatic patients will walk through the door in coming weeks, and the usual N95 suppliers are struggling to keep up with demand.

University Hospital wanted a contingency plan. Protecting our workforce must be our top priority during this crisis. So, Tommye Austin, University Health System’s chief nurse executive and others, began exploring alternatives and conferring with healthcare experts around the country.

What they found was that they could safely reuse N95 masks once they are sterilized with a hydrogen peroxide process the hospital already uses to decontaminate other medical equipment, including surgical instruments.

“We already know it works, so why not use it?” asks Austin. “We are just repurposing it.”

Researchers at the University of Massachusetts Amherst report that a used N95 mask sterilized with hydrogen peroxide gas blocked infectious particles as effectively as an unused mask, which screens out 95% of airborne particles.

The Centers for Disease Control found the process does not damage filtration or change the fit of the mask which must be snug on the wearer’s face.

With the assurance of science and testing, University Hospital’s sterilization department has begun using hydrogen peroxide to decontaminate N95s.

At the end of a shift, healthcare employees place their masks in individual bags. The sterilization team examines the masks and discards those that are damaged or soiled.

“If we receive masks with lipstick, foundation or blush on them we are not reprocessing them. We consider them soiled,” explains Monica Chavez, the processing department’s director. “If they have moisture of some sort on them, we will not reprocess them, either.”

Masks that pass a visual test are then sent through a Sterrad machine, which bombards them with the gas. A bio-indicator accompanying the masks shows when all of the germs have been killed.

The process, which takes several hours, allows each N95 to be worn by the same healthcare worker four times. The hospital is currently sterilizing about 50 N95s a day. While that’s not a replacement for the continued effort to acquire new masks, it greatly extends the hospital’s supply.

“If this can helps us prolong (the use of our PPE), that’s what my hope is,” says Chavez.

Brittney Wagner, the department’s assistant director feels pride in being able to provide effective equipment for her frontline colleagues.

“We’re here to help our family give the best they can give, by us providing the best we can for them,” she says.