VT professor tests effectiveness of N95 masks used after sanitation

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BLACKSBURG, Va. (WDBJ) — With N95 masks in short supply, hospitals are turning to methods like hydrogen peroxide vapor to decontaminate them for reuse.

Photo courtesy Linsey Marr

But just how effective are masks once they’ve been sterilized?

Virginia Tech engineering professor Linsey Marr wanted to find out.

“We found that even up to 10 cycles of sterilization, the masks were still as good as new in terms of how well they protected healthcare workers against droplets and particles, and keep those from getting through,” said Marr.

She and her team tested the effectiveness of sterilized N95 masks against brand new masks by pulling air through them, similar to how water runs through a coffee filter.

The fewer particles that pass through, the safer the mask.

“We use special instruments to measure how many particles there are in this chamber, in this bag, in front of the filter and then also behind the filter, the air that we pull through the filter,” said Marr.

Marr says knowing that these masks are safe for re-use up to ten times gives hospital and frontline workers the peace of mind they need to keep going.

“Having this knowledge allows the healthcare workers to keep doing their job while making sure that they are being protected from exposure to the virus,” said Marr.

These Virginia Tech researchers are also working to figure out which at-home mask materials best trap virus particles.

Towels and cotton t-shirts work the worst out of the items they’ve tested, stopping only 10 percent of particles.

One of the best has been microfiber cloths, trapping up to 80 percent of particles, according to Marr.

“They are able to weave them really close together so there’s not a lot of gaps and it makes it really hard for particles to kind of weave their way through there.”

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