Researchers develop novel disinfection process for N95 respirators

A multidisciplinary team developed a process that uses vaporized hydrogen peroxide, or VHP, to disinfect N95 respirators, according to a paper published in the Journal of the American College of Surgeons.

During previous pandemics as well as the current COVID-19 pandemic, researchers have developed disinfection processes for N95 respirators with “encouraging results” — such as ultraviolet germicidal irradiation — but the only disinfection processes approved by the FDA use VHP, according to Julie Grossman, MD, a surgical resident at Washington University School of Medicine in St. Louis, and colleagues.Researchers added that “these technologies can be difficult to obtain in the setting of the significant demand around the globe.”

Grossman and colleagues also noted that though a previous study showed “significant reductions” in viral load on N95 respirators via ultraviolet germicidal irradiation, the disinfection of straps via that method may be incomplete.

The process that Grossman and colleagues developed starts with doffing the respirator and placing it into a Tyvek (Crosstex) pouch. The pouch was then:

• sealed with the self-sealing adhesive strip and labelled with the worker’s employee identification number or name, hospital, department, and the unit’s location;
• placed in a soiled collection bin and transported to the health care facility’s VHP room within 12 hours (in the study, this room was monitored with a hydrogen peroxide sensor [PAC III, Draeger]);
• placed in a staggered fashion on wire racks 47 inches wide, 18 inches deep and 76 inches tall, with the largest part of the pouch facing up;
• disinfected using the Bioquell Z-2 (Bioquell) device for 4.5 hours, until the H₂O₂ level has reached at least 700 parts per million; and
• removed from the VHP room and placed in an off-gassing/aeration room for 2 hours.

The researchers experimented with the placement of the pouches on the racks, packing some pouches tightly against one another and others loosely.

“Biological indicators placed within these pouches demonstrated successful disinfection for either configuration, and all N95 respirators passed quantitative fit testing,” they wrote.

When a respirator’s H₂O₂ read 0 parts per million, it can be used for up to 3 weeks before the disinfection process needs to be repeated, according to a press release. The VHP process could disinfect up to 1,500 respiratory masks daily and is best suited for health care systems of 31,000 employees or less, the researchers wrote.

Shaina Eckhouse, MD, FACS, study co-author and assistant professor of surgery at Washington University School of Medicine in St Louis, added that a multidisciplinary approach like theirs involving environmental health and safety, medicine and facility management is key to successfully implementing the disinfection process.

“Having the infrastructure already in place would improve the ease of deploying an N95 disinfection process," Eckhouse said in the press release. – by Janel Miller

Disclosures: The authors report no relevant financial disclosures.