Novel decontamination procedure for N95 masks appears safe, effective
Researchers from Nebraska Medicine have developed a procedure for decontaminating N95 respirators using ultraviolet germicidal irradiation, according to a publication on the process released by the institution.
“The ongoing pandemic of SARS-CoV-2 resulting in COVID-19 has severely stressed the worldwide health care system and has created dangerous shortages of personal protective equipment (PPE), including N95 filtering facepiece respirators (N95 FFRs),” John J. Lowe, PhD, assistant vice chancellor for inter-professional health security training and education and associate professor of environmental, agricultural and occupational health in the department of environmental, agricultural and occupational health at the University of Nebraska Medical Center, and colleagues wrote. “In an effort to extend the stockpile of N95 FFRs at our institution, we developed a decontamination procedure involving the delivery of ultraviolet germicidal irradiation (UVGI) to used N95 FFRs.”
According to the paper, UVGI has demonstrated effectiveness for inactivating a broad group of human pathogens, including coronaviruses and other human respiratory viruses, and human respiratory viruses, including coronaviruses, on several types of N95 FFRs. In addition, the level of UVGI required to inactivate human respiratory viruses “are well below the level of irradiation that adversely affects the fit and filtration characteristics of N95 FFRs,” Lowe and colleagues wrote. The researchers found UVGI can be safely administered when the proper safeguards are in place, leading them to outline decontamination methods for N95 FFRs using UVGI.
According to the paper, used N95 FFRs are secured on wires that are strong across a room. Two UVGI towers in the room are equipped with eight 254 nm bulbs that produce 200 w/cm2 at 10 feet distance for a dosage of 12 mJ/minute. The respirators are then exposed to UVGI at a rate of 60 mJ/cm2 though single-stranded RNA viruses, such as SARS-CoV-2, are generally inactivated by a UVGI exposure of 2 to 5 mJ/cm2, according to the researchers. UVGI exposure is monitored to ensure that the necessary amount of exposure is achieved.
Lowe and colleagues will “decontaminate and reuse the N95 FFRs multiple times until respirator fit is impacted,” according to the paper.
“We believe a variety of UV light sources could be used in a similar fashion, including UV equipped biosafety or sterilization cabinets or other UV disinfection systems and that this method can be applied to a variety of other critical items, such as procedure masks.” – by Caitlyn Stulpin
Nebraska Medicine. N95 filtering facepiece respirator ultraviolet germicidal irradiation (UVGI) process for decontamination and reuse. https://www.nebraskamed.com/sites/default/files/documents/covid-19/n-95-decon-process.pdf. Accessed April 6, 2020.
Disclosures: Healio could not confirm the authors’ relevant financial disclosures at the time of publication.