Scalable, effective, and rapid decontamination of SARS-CoV-2 contaminated N95 respirators using germicidal ultraviolet C (UVC) irradiation device

Mattheos Koffas,Richard Vincent,Michael Schotsaert,Brigitte L. Arduini,Jason L. Davis,Raveen Rathnasinghe,Adolfo García-Sastre,Deepak Vashishth,Mohammed Alnaggar,Priti Balchandani,Robert F. Karlicek,Sonia Jangra,Anthony Costa,Bowen Wang

doi:10.1038/s41598-021-99431-5

Mattheos Koffas, Richard Vincent + Show 12 more

Open Access

https://doi.org/10.1038/s41598-021-99431-5

Copy DOI

Abstract

Particulate respirators such as N95s are an essential component of personal protective equipment (PPE) for front-line workers. This study describes a rapid and effective UVC irradiation system that would facilitate the safe re-use of N95 respirators and provides supporting information for deploying UVC for decontamination of SARS-CoV-2 during the COVID-19 pandemic. To assess the inactivation potential of the proposed UVC germicidal device as a function of time by using 3 M 8211-N95 particulate respirators inoculated with SARS-CoV-2. A germicidal UVC device to deliver tailored UVC dose was developed and test coupons (2.5 cm2) of the 3 M-N95 respirator were inoculated with 106 plaque-forming units (PFU) of SARS-CoV-2 and were UV irradiated. Different exposure times were tested (0–164 s) by fixing the distance between the lamp and the test coupon to 15.2 cm while providing an exposure of at least 5.43 mWcm−2. Primary measure of outcome was titration of infectious virus recovered from virus-inoculated respirator test coupons after UVC exposure. Other measures included the method validation of the irradiation protocol, using lentiviruses (biosafety level-2 agent) and establishment of the germicidal UVC exposure protocol. An average of 4.38 × 103 PFU ml−1 (SD 772.68) was recovered from untreated test coupons while 4.44 × 102 PFU ml−1 (SD 203.67), 4.00 × 102 PFU ml−1 (SD 115.47), 1.56 × 102 PFU ml−1 (SD 76.98) and 4.44 × 101 PFU ml−1 (SD 76.98) was recovered in exposures 2, 6, 18 and 54 s per side respectively. The germicidal device output and positioning was monitored and a minimum output of 5.43 mW cm−2 was maintained. Infectious SARS-CoV-2 was not detected by plaque assays (minimal level of detection is 67 PFU ml−1) on N95 respirator test coupons when irradiated for 120 s per side or longer suggesting 3.5 log reduction in 240 s of irradiation, 1.3 J cm−2. A scalable germicidal UVC device to deliver tailored UVC dose for rapid decontamination of SARS-CoV-2 was developed. UVC germicidal irradiation of N95 test coupons inoculated with SARS-CoV-2 for 120 s per side resulted in 3.5 log reduction of virus. These data support the reuse of N95 particle-filtrate apparatus upon irradiation with UVC and supports use of UVC-based decontamination of SARS-CoV-2 during the COVID-19 pandemic.

Highlights

Inactivation of N95 respirator test coupons spiked with LV‐EGFP
Further reduction of approximately 2 logs was observed by an exposure of 54 s and by 120 s, total inactivation was apparent by the lack of plaque forming units (PFU) derived from the respective experimental settings (T = 120 s per side 3.6 Log[10] reduction)
Healthcare workers, extensively rely on filtering facepiece respirators (FFR) such as N95 respirators to minimize the risk of contraction and transmission of SARS-CoV-2

Summary

Introduction

Health and Emerging Pathogens Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 6Smart Lighting Engineering Research Center, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 7Department of Electrical Computer and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 8Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 9Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 10Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 11Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 12Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 13Department of Medicine, Section of General Internal Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 14Department of Biomedical Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 15BioMedical Engineering and Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA. 16These authors contributed : Raveen Rathnasinghe and Robert F. As the extent of this pandemic resulted in the long-anticipated shortage of FFR and other facemasks, the need for more PPE supplies across the world escalated s ignificantly[5] Such a situation negatively impacted healthcare settings, putting frontline workers in a vulnerable position, potentially resulting in a collapse of the healthcare system. This was further corroborated by the World Health Organization (WHO) stating that insufficient supply of such PPEs would put essential frontline workers at the risk of being exposed to SARS-CoV-2, which would further facilitate the spread of this contagious d isease[6]. Given the variability of SARS-CoV-2 viral survivorship on different surfaces and the close, long-term contact of reused respirators with the face, a scalable, reliable, cost-effective disinfection procedure that would enable the safe reuse of PPE is of global interest[11]

Objectives

Methods

Results

Conclusion