Light propagation within N95 Filtered Face Respirators: A simulation study for UVC decontamination

This study presents numerical simulations of UVC light propagation through seven different filtered face respirators (FFR) to determine their suitability for UV germicidal inactivation (UVGI). UV propagation was modelled using the FullMonte program for two external light illuminations. The optical properties of the dominant three layers were determined using the inverse adding doubling method. The resulting fluence rate volume histograms and the lowest fluence rate recorded in the modelled volume, sometimes in the nW cm-2, provide feedback on a respirator’s suitability for UVGI and the required exposure time for a given light source. While UVGI can present an economical approach to extend an FFR’s useable lifetime, it requires careful optimization of the illumination setup and selection of appropriate respirators. ![Figure][1] ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement Funding for this study was provided through the Ontario Ministry of Economic Development and Trade, through the Ontario Research Fund Grant ORF RE08 022 and Princess Margaret Cancer Centre, the Princess Margaret Cancer Foundation, and Ontario Ministry of Health, NSERC/Intel Industrial Research Chair in Programmable Silicon IRC:428842 16 and an IBM Faculty Research Award. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: no REB approval was required for this study All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The raw data and all fluence-rate-volume-histogram https://www.eecg.utoronto.ca/~vaughn/fullmonte/n95\_decon/n95\_decon.html [https://www.eecg.utoronto.ca/~vaughn/fullmonte/n95\_decon/n95\_decon.html][2] [1]: pending:yes [2]: https://www.eecg.utoronto.ca/~vaughn/fullmonte/n95_decon/n95_decon.html