Upper-room ultraviolet air disinfection might help to reduce COVID-19 transmission in buildings

Abstract

As the world economies get out of the lockdown imposed by the COVID-19 pandemic, there is an urgent need to assess the suitability of known technologies to mitigate COVID-19 transmission in confined spaces such as buildings. This feasibility study looks at the method of upper-room ultraviolet (UV) air disinfection that has already proven its efficacy in preventing the transmission of airborne diseases such as measles and tuberculosis. Using published data from various sources it is shown that the SARS-CoV-2 virus, which causes COVID-19, is highly likely to be susceptible to UV damage while suspended in air irradiated by UV-C at levels that are acceptable and safe for upper-room applications. This is while humans are present in the room. Both the expected and worst-case scenarios are investigated to show the efficacy of the upper-room UV-C approach to reduce COVID-19 air transmission in a confined space with moderate but sufficient height. Discussion is given on the methods of analysis and the differences between virus susceptibility to UV-C when aerosolised or in liquid or on a surface.

The efficacy of ultraviolet light-emitting technology against coronaviruses: a systematic review

“…The possible role of UV irradiation as environmental sterilization adjunct for standard protocols against a wide range of pathogens (viruses and bacteria) or air disinfection method for viruses only was systematically assessed by, respectively, Ramos et al [ 76 ] and Beggs et al [ 77 ]; Sharafi et al [ 78 ] and Shimabukuro et al [ 79 ] focused specifically on SARS-CoV-2.…”

Evaluation of indoor disinfection technologies for airborne disease control in hospital

“…Based on the published literature regarding UV deactivation of different airborne coronavirus types, the range of ‘ A R ’ value is 0.0377–0.590 (J/m 2 ). 17 However, accurate values of disinfection coefficient are difficult to obtain by theoretical calculation. Previous research utilized experimental data to assume ‘ A R ’ value in numerical simulation of UV disinfection.…”

The Facility Infection Risk Estimator™: A web application tool for comparing indoor risk mitigation strategies by estimating airborne transmission risk

“…Reported susceptibility parameter (Z), or UV rate constant, values (m 2 /J) for SARS-CoV-2 include the suggestion 16 for 0.377 (best-case) and 0.0377 m 2 /J (worst-case) and the suggestion 71 of 0.05524 m 2 /J. At this point, there are no known studies linking the susceptibility parameter (Z) for SARS-CoV-2 to RH, so for the purposes of this model, the average of 0.377 and 0.0377 m 2 /J was used (0.207 m 2 /J).…”