Yale researchers find a way to sterilize and recycle thousands of respirator masks
Connecticut hospitals are receiving more patients ill with COVID-19 as the new coronavirus continues to spread rapidly.
Public health experts predict that hospitalization rates will get worse in the coming weeks, putting a burden on health care professionals who are also trying to protect themselves and other patients from becoming infected.
N95 respirator masks are considered one of the best types of personal protective equipment against liquids and airborne particles that contain a virus, but a shortage of new masks at hospitals nationwide has forced researchers and scientists to come up with alternative options, like recycling equipment.
“To put [it] in context, really the times we used N95s before this, most commonly, were things like tuberculosis and other more rare infectious pathogens,” said Dr. Patrick Kenney, medical director of the supply chain for Yale Medicine and Yale New Haven Health.
“Right now, we’re using manyfold the number of N95s that we normally did. At our prior usage rate, we had a several years’ worth of supply on hand,” he said, “but at the current usage rate and what we’re projecting over the next few weeks, that supply is going to dwindle very rapidly.”
As of Monday afternoon, 517 people with confirmed cases of COVID-19 were hospitalized, according to the Connecticut Hospital Association.
Other hospitalized patients are awaiting test results.
With the increased demand in care, health care workers are burning through more supplies of gloves, masks, gowns and other equipment necessary to prevent infection. Kenney said it’s also become a manufacturing issue on a global scale.
“The United States and many other countries import N95 respirators and other medical devices from a variety of different countries, including China. Even when those factories come back online and increase production, there are also distribution problems,” he said. “So, the entire supply chain, from the raw materials to the actual fabrication of the respirators out of factory, to all the different transportation that happens to get the respirators into the hands of a caregiver, every aspect of it has been impacted.”
Typically, a respirator mask, which is different from and more effective than a surgical mask, is used by a health care worker once for each patient encounter and then discarded. But as supply dwindles, Connecticut hospitals have asked health care workers to reuse masks for a limited time.
It’s a method recommended by the U.S. Centers for Disease Control and Prevention during crisis and pandemic situations. The federal agency also states that health care systems may use respirators beyond the manufacturer’s shelf life.
The CDC also has guidance about what to do when all supplies of new respirator and surgical masks and other equivalent equipment runs out. As a last resort, “it may be necessary for [health care professionals] to use masks that have never been evaluated … or homemade masks,” which could include improvised mouth and nose covers with bandanas, scarves or other materials.
But Kenney and a research team at Yale think they’ve found a better alternative to that situation. It involves identifying respirator masks that can be recycled.
“What we’re talking about is, instead of throwing away the respirator at the end of someone’s shift, is to sort through them and to find the ones that still seem to be in good shape,” he said. “They’re not visibly soiled, there’s no tears, there’s no holes, the respirator looks intact.”
Then the masks are suspended on racks in a room, “filling every nook and cranny,” and put through a re-processing procedure for sterilization, Kenney said.
“We’ve repurposed a machine that’s normally used in the hospital to fumigate hospital rooms after a patient who has an infection is discharged. And the way this machine works is that it fills the room with hydrogen peroxide vapor,” he said.
The chemical process takes about five hours, with additional time to extract the chemicals from the room and the masks. In their preliminary research, Kenney said the vaporized process killed three types of viruses selected as proxies for the SARS-CoV-2 virus that’s causing the current pandemic. The mask filtration capabilities remained intact.
The health care system has four working fumigation machines and four designated rooms for the process. Kenney estimates that in theory, they could recycle up to 15,000 respirator masks a day if necessary.
The recycled masks are being put in storage for now.
“The reason for that is we have an adequate supply of new respirators for normal operations,” Kenney said. “Our No. 1 goal by far is the safety of our staff and patients. And we think this is safe, but we’re not going to use this until it comes to the bandanas and scarves type of scenario.”
Kenney said his team is willing to share the process with other health care systems looking for solutions to their decreasing supplies of N95 respirator masks.
“Although we’re not necessarily encouraging others to do this, we certainly want them to be aware about it, and to see if they can repurpose the machine that they may already have in their facility to a new purpose to keep their workers safe,” he said.
But Kenney warned that study results are awaiting confirmation by an independent laboratory. It hasn’t yet been peer reviewed, which he says is a vital aspect of the scientific process — but it can be time consuming.
“Time is one thing that the coronavirus crisis really has not afforded us, so we’re moving forward.”
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