In hospitals and labs, researchers find ways to clean and reuse masks
Michigan’s largest healthcare system has already taken the extraordinary step of disinfecting and reusing some N95 masks, a crucial piece of personal protection equipment for healthcare workers caring for COVID-19 patients. Elsewhere in the state, researchers are developing similar processes to reuse the masks in case supplies run out.
“We still have small supplies of N95s, and they continue to get replenished, but not as fast as we need them to,” said Dr. Sam Flanders, chief quality officer at Beaumont Health. “And certain sizes like the smaller masks are especially scarce. So this process has become very important to us.”
In terms of supplying enough personal protective equipment for Beaumont staff across the eight-hospital system, the N95 masks are the most pressing concern. Beaumont Health bioengineers devised a three-step process to disinfect the masks to be reused by the same wearer.
“This is a time of a national emergency and this would never be done under normal circumstances,” Flanders said.
To disinfect the masks, they’re first collected from healthcare workers across Beaumont’s eight hospitals. According to Flanders, they’re labeled, put in a bag, and transported to the “ultraviolet disinfection unit” at the Beaumont Royal Oak hospital. The masks are exposed to ultraviolet light in a process that takes up to eight minutes. After that, the masks are put in new bags, and heated to 150-160 degrees Fahrenheit for one hour. Then they’re returned to the same people who originally used them.
“If anything was missed by the ultraviolet light, viruses don’t like being heated up, and they tend to be killed pretty easily in heat,” Flanders said. “In the very unlikely event that anything is left over, we’re just giving it back to the person that already had it. So we feel with those three steps in place that is very, very safe.”
"This is a time of a national emergency and [reusing N95 masks] would never be done under normal circumstances." - Dr. Sam Flanders, Beaumont Health
Researchers at Michigan State University have been able to disinfect N95 masks using commercial ovens and vaporous hydrogen peroxide. Dr. Norman Beauchamp, executive vice president for Health Sciences at MSU, said researchers disinfected 295 masks over the weekend, but are waiting for FDA approval to use the method.
“We’re not officially having people wear these until we get the FDA approval,” Beauchamp said. “We’re hopeful we can get it done within a week.”
He says waiting for a FDA approval is simply another precaution.
“Truth be known, the protocol is really well established," Beauchamp said. "We do know that at this temperature viruses will be killed.”
Similarly, researchers at the University of Michigan have been working to establish a scalable process for recycling N95 masks, testing both to determine effective methods to kill virus particles on the masks, and testing how many times N95 masks can be treated before the masks can’t be used.
Associate professor of civil and environmental engineering Krista Wigginton is part of the team that’s tested disinfection treatment methods; namely heat (dry and humid), UV light, and hydrogen peroxide vapor.
“They all seem to be effective, that’s the good thing,” Wigginton said.
She said they’re using a combination of different treatments to be even more confident in the results. U of M researchers aren’t testing masks that have been worn by healthcare workers. In the experiment they’re putting different viruses on masks, then test different disinfection methods and test their efficacy, as well as monitoring mask fit.
“We’re testing against viruses that are pretty similar to COVID-19. Close enough that we feel there wouldn’t be any major differences.” Wigginton said. “We’re testing four different viruses … two of them in particular have the same kind of structure as COVID-19. That’s the way we felt most comfortable about validating.”
Michigan Medicine, the U of M healthcare system, currently has enough personal protection equipment to protect Michigan Medicine staff, according to Mary Masson, director of public relations at Michigan Medicine. Masson declined to comment about reuse or disinfection strategies for N95 masks but said the system is studying “multiple techniques”.
At Beaumont, Flanders said masks will be reused up to three times, but that’s not a decision based in science.
“We feel we could probably increase that number of disinfection times, and we may actually do that, if we need to, to preserve more quantities of these masks,” Flanders said.