Extreme Exposure to Filtered Far-UVC: A Case Study^†

TY - JOUR

T1 - Extreme Exposure to Filtered Far-UVC

T2 - A Case Study†

AU - Eadie, Ewan

AU - Barnard, Isla

AU - Ibbotson, Sally H.

AU - Wood, Kenneth

N1 - © 2021 The Authors. Photochemistry and Photobiology published by Wiley Periodicals LLC on behalf of American Society for Photobiology

PY - 2021/2/3

Y1 - 2021/2/3

N2 - Far-UVC devices are being commercially sold as “safe for humans” for the inactivation of SARS-CoV-2, without supporting human safety data. We felt there was a need for rapid proof-of-concept human self-exposure, to inform future controlled research and promote informed discussion. A Fitzpatrick Skin Type II individual exposed their inner forearms to large radiant exposures from a filtered Krypton-Chloride (KrCl) far-UVC system (SafeZoneUVC, Ushio Inc., Tokyo, Japan) with peak emission at 222 nm. No visible skin changes were observed at 1500 mJ cm −2; whereas, skin yellowing that appeared immediately and resolved within 24 h occurred with a 6000 mJ cm −2 exposure. No erythema was observed at any time point with exposures up to 18 000 mJ cm −2. These results combined with Monte Carlo Radiative Transfer computer modeling suggest that filtering longer ultraviolet wavelengths is critical for the human skin safety of far-UVC devices. This work also contributes to growing arguments for the exploration of exposure limit expansion, which would subsequently enable faster inactivation of viruses.

AB - Far-UVC devices are being commercially sold as “safe for humans” for the inactivation of SARS-CoV-2, without supporting human safety data. We felt there was a need for rapid proof-of-concept human self-exposure, to inform future controlled research and promote informed discussion. A Fitzpatrick Skin Type II individual exposed their inner forearms to large radiant exposures from a filtered Krypton-Chloride (KrCl) far-UVC system (SafeZoneUVC, Ushio Inc., Tokyo, Japan) with peak emission at 222 nm. No visible skin changes were observed at 1500 mJ cm −2; whereas, skin yellowing that appeared immediately and resolved within 24 h occurred with a 6000 mJ cm −2 exposure. No erythema was observed at any time point with exposures up to 18 000 mJ cm −2. These results combined with Monte Carlo Radiative Transfer computer modeling suggest that filtering longer ultraviolet wavelengths is critical for the human skin safety of far-UVC devices. This work also contributes to growing arguments for the exploration of exposure limit expansion, which would subsequently enable faster inactivation of viruses.

KW - Physical and Theoretical Chemistry

KW - Biochemistry

KW - General Medicine

UR - https://www.scopus.com/pages/publications/85100354686

U2 - 10.1111/php.13385

DO - 10.1111/php.13385

M3 - Article

C2 - 33471372

SN - 0031-8655

VL - 97

SP - 527

EP - 531

JO - Photochemistry and Photobiology

JF - Photochemistry and Photobiology

IS - 3

ER -