Predicting airborne coronavirus inactivation by far-UVC in populated rooms using a high-fidelity coupled radiation-CFD model

Andrew G Buchan,Liang Yang,Kirk D Atkinson

doi:10.1038/s41598-020-76597-y

Abstract

There are increased risks of contracting COVID-19 in hospitals and long-term care facilities, particularly for vulnerable groups. In these environments aerosolised coronavirus released through breathing increases the chance of spreading the disease. To reduce aerosol transmissions, the use of low dose far-UVC lighting to disinfect in-room air has been proposed. Unlike typical UVC, which has been used to kill microorganisms for decades but is carcinogenic and cataractogenic, recent evidence has shown that far-UVC is safe to use around humans. A high-fidelity, fully-coupled radiation transport and fluid dynamics model has been developed to quantify disinfection rates within a typical ventilated room. The model shows that disinfection rates are increased by a further 50-85% when using far-UVC within currently recommended exposure levels compared to the room’s ventilation alone. With these magnitudes of reduction, far-UVC lighting could be employed to mitigate SARS-CoV-2 transmission before the onset of future waves, or the start of winter when risks of infection are higher. This is particularly significant in poorly-ventilated spaces where other means of reduction are not practical, in addition social distancing can be reduced without increasing the risk.

Highlights

The coronavirus pandemic has put hospitals and long term care facilities under considerable stretch
High fidelity modelling is essential, and here we present the first coupled radiation transport and fluid dynamics simulator, based on the Boltzmann Transport and Navier–Stokes equations with integrated Large Eddy Simulation (LES) turbulence models, for viral inactivation within atmospheres
This model was used to study the far-UVC inactivation of aerosolised human coronavirus in a single occupancy private room, a representative environment found in hospitals and long-term care facilities

Summary

Introduction

The coronavirus pandemic has put hospitals and long term care facilities under considerable stretch. Quantifying the rate of far-UVC viral inactivation within a general room is complex and multiphysics in nature It requires both radiation and atmospheric flow calculations where objects within rooms add complication as they obstruct both the light propagation and air flows, casting shadows and inducing eddies and turbulent structures. The use of LES m odels[24] provide more detailed descriptions of viral transport over other modelling methods, such as Reynolds Averaged Navier–Stokes[21,23] or analytical zone-mixing m ethods[23,25], and despite their increased computational requirement, and limited use, their importance is being recognised in the field of atmospheric viral transport p redictions[24] This model was used to study the far-UVC inactivation of aerosolised human coronavirus in a single occupancy private room, a representative environment found in hospitals and long-term care facilities.

Methods

Results

Conclusion