N95 Masks Can Be Decontaminated at Least 25 Times, Study Shows

Some N95 masks can be safely cleaned and recycled several times without losing their effectiveness, according to a study published last week in the American Journal of Infection Control.

In view of supply shortages in personal protective equipment that occurred during the pandemic's early months, researchers said the study's findings demonstrate a possible way for health care facilities to fill in supply gaps during future health emergencies.

The study was conducted by researchers in Boston at Beth Israel Deaconess Medical Center and the Massachusetts Institute of Technology, according to a January 6 news release from the Association for Professionals in Infection Control and Epidemiology (APIC). Over the course of the study, researchers put seven N95 masks through a process involving vaporized hydrogen peroxide (VHP), which they noted in the release is a "standard decontamination approach."

N95 masks reprocessed 25 times
A new study suggests some N95 masks can be safely cleaned and recycled up to 25 times when a procedure involving vaporized hydrogen peroxide is used. Above, 3M brand N95 particulate respirators are displayed on July 28, 2020, in San Anselmo, California. Justin Sullivan/Getty Images

After going through the VHP process 25 times, the N95 masks were found to retain a 95 percent filtration efficiency or greater, researchers said.

Every time a mask was put through the VHP process, researchers assessed it to determine the extent to which its user seal, fit and filtration were affected. They found that "even after 25 decontamination cycles there were no alterations to respiratory integrity or filtration efficiency among the seven N95 respirators the researchers evaluated," the release said.

Ann Marie Pettis, the 2021 president of APIC, encouraged investing in VHP so health care facilities will be prepared for future epidemics.

"The findings from this study are encouraging and valuable, particularly given the N95 respirator shortage we experienced during the COVID-19 pandemic," Pettis said in the release.

The Beth Israel Deaconess Medical Center said in a release that its staff members used the VHP process while reusing N95 masks as health care facilities throughout the U.S. were having supply shortages during the pandemic's early months. The center said it followed the U.S. Centers for Disease Control and Prevention's guidance on reusing N95 masks during shortages. The CDC acknowledged VHP as one of the strategies that "has shown the most promise" in its "potential" to decontaminate the masks.

As of May 2021, the CDC said that supplies of N95 masks in the U.S. have rebounded and that health care facilities "should not be using crisis capacity strategies at this time," though the agency's steps to determine when masks should be reused are still accessible online.

Christina Yen, an infectious diseases physician who is the study's leading author, said the researchers' findings could be of use in dealing with mask shortages in upcoming epidemics.

"It is important that we now find ways to scale and translate this capability to smaller hospitals and resource-limited healthcare settings that could benefit just as much—perhaps more—from this type of personal protective equipment reprocessing in future disaster scenarios," Yen said in the APIC's release.

Newsweek reached out to the CDC for comment but did not hear back before publication.