Fast inactivation of coronavirus in filtering-facepiece respirators in a reflective cylindrical UV-C chamber

Marilia Wellichan Mancini; Luciana Almeida-Lopes; Paulo Sérgio Bossini; Gislaine Santos Jacintho; Junko Tsukamoto; Clarice Weis Arns

doi:10.1016/j.jpap.2022.100151

Fast inactivation of coronavirus in filtering-facepiece respirators in a reflective cylindrical UV-C chamber

J Photochem Photobiol. 2022 Dec:12:100151. doi: 10.1016/j.jpap.2022.100151. Epub 2022 Nov 18.

Authors

Marilia Wellichan Mancini¹, Luciana Almeida-Lopes¹, Paulo Sérgio Bossini¹, Gislaine Santos Jacintho², Junko Tsukamoto², Clarice Weis Arns²

Affiliations

¹ Institute of Research and Education in the Health Area (NUPEN), São Carlos, SP, Brazil.
² Animal Virology Laboratory, Department of Genetics, Evolution, Microbiology and Immunology, Institute of Biology, University of Campinas, Campinas, SP, Brazil.

Abstract

Objective: We report on the development and characterization of a UV-C (λ = 200 - 280 nm, λ_peak = 254 nm) chamber designed for the rapid disinfection of N95 class filtering-facepiece respirators contaminated with SARS-CoV-2 coronaviruses. The device was evaluated against Betacoronavirus strain MHV-3 and its virucidal capacity was evaluated as a function of different applied UV-C doses (UV-C exposure times of 60 s, 120 s, 180 s, and 240 s) using two types of respirators geometry (shell and two-panel shapes, 3M 8801 H and 9920 H, respectively), at eight points of the respirators.

Background: Most chemical disinfection methods are not recommended for N95 masks. UV-C light provided by UVGI lamps (254 nm) is an effective physical agent against viruses and bacteria due to direct photochemical harming effect on DNA/RNA, and can provide rapid disinfection for personal protective equipment such as N95/PFF2 masks.

Results: The device reached a mean elimination rate of 99.9999% of MHV-3 inoculated into all the assessed different points on the tested PFF2 respirator models in a UV-C cycle of just 60 s. Statistical analysis performed through Person´s chi-square test showed no correlation between the viral infectivity reduction and the viral inoculation point (p = 0.512) and the tested respirator models (p = 0.556). However, a correlation was found between the exposure time and the viral infectivity reduction (p = 0.000*), between UV-C and no UV-C exposure. All the tested UV-C exposure times (60 s, 120 s, 180 s, and 240 s) provided the same reduction in infection rates. Therefore, 60 s was confirmed as the minimum exposure time to achieve a 99.9999% or 6 Log reduction in MHV-3 coronavirus infection rates in the PFF2 samples tested in the device.

Conclusions: We conclude that the assessed UV-C chamber for the inactivation of MHV-3 coronavirus in N95/PFF2 standard masks can be a promising tool for effective and rapid disinfection of coronaviruses, including SARS-CoV-2 virus.

Keywords: COVID-19; Coronavirus MHV-3; FFR; Light/Light source; N95; PFF2; Photobiology; Photomedicine; Reuse; UV-C light; UV-C, Microbiology.