N95 Filtering Facemask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse

The ongoing pandemic of SARS-CoV-2 resulting in COVID-19 has severely stressed the worldwide healthcare system and has created dangerous shortages of personal protective equipment (PPE) including N95 filtering facepiece respirators (N95 FFRs). 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. The evidence base supporting this program includes: 1) UVGI has been shown to effectively inactivate a wide range of human pathogens including coronaviruses and other human respiratory viruses; 2) UVGI has been demonstrated to inactivate human respiratory viruses, including coronaviruses, on various models of N95 FFRs; 3) levels of UVGI needed to inactive human respiratory viruses are well below the level of irradiation that adversely affects the fit and filtration characteristics of N95 FFRs; and 4) UVGI can be safely administered when appropriate safeguards are in place. Herein, we briefly describe our procedure to decontaminate and reuse N95 FFRs.

Used N95 FFRs are subjected to UVGI at an exposure of 60 mJ/cm2. Single-stranded RNA viruses, such as SARS-CoV-2, are generally inactivated by UVGI exposure of 2-5 mJ/cm2 (1). Thus, the UVGI exposure we have chosen exceeds, by at least several fold, the amount of exposure needed to inactivate SARS-CoV-2 and provides a wide margin of safety. Respirators are secured on wires that are strung across a room with two UVGI towers (ClorDiSys UVGI Light System, https://www.clordisys.com/products.php) on either side. These UVGI towers are equipped with eight 254 nm bulbs, thesebulbs are routinely used in biosafety cabinets and produce 200 μw/cm2 at 10 feet distance for a dosage of 12 mJ/minute. We monitor the delivered UVGI exposure dose with a UVGI meter that can be initiated and monitored from outside the room to verify that the desired exposure has been achieved. As UVGI can cause damage to eyes and skin, this protects oru UVGI associate’s safety. We plan to decontaminate and reuse the N95 FFRs multiple times until respirator fit is impacted (2-4). Prior to initiating the decontamination program, the walls and ceiling were covered with a UV-reflective coating (https://lumacept.com) with which our group had experience (5). Our program initially involved the units with high N95 FFR use such as the emergency department and our COVID-19 ward, but we plan to rapidly expand to ambulatory settings. 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. The method described below is a result of multiple tests, a review of the scientific literature, and incorporation of current institutional practice.  (Nebraska Medicine).

John J Lowe, Katie D Paladino, Jerald D Farke, Kathleen Boulter, Kelly Cawcutt, Mark Emodi, Shawn Gibbs, Richard Hankins, Lauren Hinkle, Terry Micheels, Shelly Schwedhelm, Angela Vasa, Michael Wadman, Suzanne Watson, and Mark E Rupp.

2020-03-21

John J Lowe, Katie D Paladino, Jerald D Farke, Kathleen Boulter, Kelly Cawcutt, Mark Emodi, Shawn Gibbs, Richard Hankins, Lauren Hinkle, Terry Micheels, Shelly Schwedhelm, Angela Vasa, Michael Wadman, Suzanne Watson, and Mark E Rupp. 2020. "N95 Filtering Facemask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse." https://www.nebraskamed.com/for-providers/covid19