Reprocessing N95 masks with hydrogen peroxide vapor

Editor's Note

This study, led by researchers from Memorial Hermann Texas Medical Center, Houston, is the first to use hydrogen peroxide vapor (HPV) technology on a large scale to reprocess N95 masks in a healthcare system.

The researchers were able to recapture and reprocess 29,706 N95 masks using HPV, with approximately 25% loss because of damage.

In a small pilot, 24 masks, representing 7 different N95 models, underwent HPV cycles, post-cycle visual inspection, and fit testing. A fit factor of more than 100 was considered acceptable for control and reprocessed masks. Of the reprocessed masks, two failed fit testing. The other 22 did not differ from the control masks.

Mask decontamination was validated using Geobacillus stearothermophilus biological indicator discs. No growth was seen on the plates containing the discs that underwent an HPV cycle.

The researchers then designed the recapture, reprocessing, and redistribution phases. Recapturing encompasses collecting the N95 masks after use for return to the reprocessing location—collection bins were placed at convenient locations on each unit in the hospital. Reprocessing consists of Bioquell HPV decontamination—the used N95s were loaded into the Bioquell room for storage before decontamination, decontamination with HPV, and a clean area for inspection. The return phase includes the process of returning masks to central supply or the original users. 

Reprocessing cost per mask is approximately $1.47. Commercial companies offer a similar services that averages $1.67-$3.25 per mask.

Having the ability to reprocess masks in house allows masks to be returned into circulation more rapidly, the researchers say.