WINNIPEG -- The University of Manitoba clinician-scientists, as well as research partners at the National Microbiology Laboratory, have identified effective techniques that may allow N95 masks to be sterilized up to 10 times.

The study was done by a group of five people, led by Dr. Anand Kumar, due to the growing concerns regarding the shortage of medical masks across the world.

“Medical masks are used by health-care workers, with the N95 providing the best protection against tiny aerosol particles that carry the novel coronavirus. At the start of the pandemic, it was clear we were going to be facing dramatically heavy demands for the N95s,” said Kumar, who’s a critical care physician at the Health Sciences Centre, in a news release.

“Our team wanted to explore how different brands and models of N95s responded to standard hospital sterilization technologies in an attempt to identify safe options for their reuse in the event of supply shortages.”

According to U of M, researchers tested four types of N95 masks and four methods of sterilization, looking at whether they could completely eliminate the virus on the masks.

The masks were then assessed for structural and functional integrity.

Kumar said the decontamination methods were “highly effective” in sterilizing the surfaces.

“No viable virus was found on any intentionally-contaminated mask following any of the decontamination procedures,” he said, noting the study wasn’t done on masks worn by healthcare workers.

Kumar said the study’s results show the decontamination methods can be done repeatedly without changing the effectiveness of the masks, pointing out two of the techniques showed no loss of filtering after multiple cleanings. However, one method, using vaporized hydrogen peroxide, isn’t widely available in North America.

One method Kumar is particularly excited about is called autoclaving.

“We successfully decontaminated these pleated, fabric N95 masks up to 10 times using autoclaving,” he said.

U of M said the researchers hope to share their findings so that other jurisdictions can look at their options and keep healthcare workers safe.

“Many institutions in highly-affected regions of the world are running out of these masks and others are rationing so that health-care workers must make use of the same masks for long periods which can lead to mask failure and increased risk to the worker,” said Kumar.

The study hasn’t undergone peer-review or been published in a medical journal.