A low cost ingenious approach for ultraviolet decontamination of N95 filtering face-piece respirators to deal with dwindling supply during the COVID-19 pandemic

Abstract

Introduction: COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus-2 is rapidly evolving and hospitals are facing the issue of shortage of personal protective equipment (PPE) due to stringent requirements of PPE use. For reuse of N95 filtering face-piece respirators (N95FFR), we prepared an ingenious cabinet with ultraviolet light C (UV-C) using scarce material available during the lockdown period. Materials and Methods: Since like many other microbiology laboratories in medical colleges, we did not have access to viruses, we could not test our product with them. We thus tested the efficacy of the cabinet to decontaminate material using 0.5 McFarland standard broth of Escherichia coli 25922. The broth was exposed to UV-C inside the cabinet for 15 and 30 minutes in Petri dishes, with and without lids. The broth was subcultured on nutrient agar plates, both pre and post exposure. We also could not test integrity and static charge of the respirators; we relied on CDC data on the same. Results: It was observed that there was at least 4 log reduction (99.99%) in the number of viable E. coli on exposure to UV-C for 15 as well as 30 minutes. The plates with glass lids on did not show any reduction in number of viable bacilli. The reduction in number of E. coli was taken as surrogate marker for the reduction of ssRNA viruses. Conclusions: UV-C inside an ingeniously made cabinet can be used to decontaminate N95 FFR in exceptional circumstances of reduced supply under lockdown conditions of a pandemic.