N95 Filtering Facemask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse
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Conservation strategies: This resource contains recommendations facilitating conservation of equipment and supplies during contingency (expected shortages) and crisis (known shortages) capacities and should not be applied as guidance when conventional capacities are available.
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).