Study Finds N95 Respirators Retain Their Effectiveness After Repeated Cleanings

Are your cleaning workers wearing masks that will protect them against the latest variant of the coronavirus? Health authorities are concerned that cloth and paper surgical masks, which are open on the ends, may not be effective against the highly contagious omicron variant of the coronavirus, Infection Control Today reports.

The U.S. Centers for Disease Control and Prevention (CDC) is considering updating its masking guidelines—which it last updated on October 25, 2021—to encourage the public to wear either N95 or KN95 respirators which have a tighter fit than cloth or paper masks.

As demand for these respirators remains high, many people may be reusing them. A study published this month in the American Journal of Infection Control found N95 respirators can be safely cleaned and re-worn up to 25 times without losing their effectiveness.

Researchers at Beth Israel Deaconess Medical Center in Boston and the Massachusetts Institute of Technology put N95 respirators through a cleaning process involving vaporized hydrogen peroxide (VHP). Each time investigators put a mask through the VHP process, they assessed the impact on the respirator’s user seal, fit, and filtration. After going through the process 25 times, researchers found the masks retained a 95% or greater filtration efficiency.

“The findings from our study expand upon previous findings and show that VHP is a relatively safe method for reprocessing N95 respirators and could help address shortages in future epidemics,” said lead study author Dr. Christina F. Yen.