Turn up the lights, leave them on, and shine them all around - numerical simulations point the way to more efficient use of Far-UVC lights for the inactivation of airborne coronavirus.

Wood, Kenneth; Wood, Andrew; Peñaloza, Camilo; Eadie, Ewan

It has been demonstrated in laboratory environments that Ultraviolet-C (UVC) light is effective at inactivating airborne viruses. However due to multiple parameters, it cannot be assumed that the air inside a room will be efficiently disinfected by commercial germicidal ultraviolet (GUV) systems. This research utilises numerical simulations of airflow, viral spread, inactivation by UVC, and removal by mechanical ventilation in a typical classroom. The viral load in the classroom is compared for conventional upper-room GUV and the emerging "far-UVC". In our simulated environment GUV is shown to be effective in both well and poorly ventilated rooms, with greatest benefit in the latter. At current exposure limits, 18 commercial far-UVC systems were as effective at reducing viral load as a single upper-room GUV. Improvements in Far-UVC irradiation distribution and recently proposed increases to exposure limits would dramatically increase the efficacy of Far-UVC devices. Modifications to current Far-UVC devices, which would improve their real-world efficacy, could be implemented now without requiring legislative change. The prospect of increased safety limits coupled with our suggested technological modifications could usher in a new era of safe and rapid whole room air disinfection in occupied indoor spaces.