31ºF

Study proves Henry Ford sterilization method makes N-95 masks safe to reuse

Researchers confirm ultraviolet light method effective in sterilizing masks

DETROIT – In the early stages of the coronavirus (COVID-19) pandemic, there wasn’t enough personal protective equipment for all health care workers.

That was especially true for N-95 respirators. Reuse became necessary and questions arose about how to sterilize masks.

Different techniques to kill the SARS-CoV-2 virus on N-95 respirators have been used, including rotation out of use for several days, heat, exposure to vaporized hydrogen peroxide and ultraviolet light.

The ultraviolet light method is what officials at Henry Ford Health System have been studying.

“Back in March, it was a pretty rough time for all of us,” said Dr. David Ozog, the chair of dermatology at the Henry Ford Health System.

The level of anxiety -- I daresay, I feel collectively, as a culture, we were near panic," Ozog said. “Our department does a lot of ultraviolet light therapy, as do a lot of dermatology departments.”

Using their expertise in ultraviolet light, they quickly determined UV-C lights could be used to kill SARS-CoV-2 on masks.

“We started implementing these devices at Henry Ford,” Ozog said. “We put them out at three different locations, and at one location, they were going through thousands of these respirators and retreating them.”

Staff members at those locations asked how Ozog knew for sure that the method was working.

“I had to be honest and say we really don’t know because we’ve never tested SARS-CoV-2,” Ozog said.

Ozog reached out to Dr. Jonathan Sexton, at the University of Michigan, where they had the unique ability to test the devices on live SARS-CoV-2 virus.

“We had received lots of contacts like this, but this one stood out to us particularly,” Sexton said. “This was about our health care workers.

“We moved forward with a collaboration that outside of COVID-19 probably wouldn’t have happened. We applied virus directly to the masks and then used the device to irradiate on both sides. What we found was with certain types of masks, that it was absolutely effective in reducing, so we basically could not detect any live virus after the mask had been exposed.”


About the Authors: