Modelling uncertainty in the relative risk of exposure to the SARS-CoV-2 virus by airborne aerosol transmission in well mixed indoor air

Jones, Benjamin; Sharpe, Patrick; Iddon, Christopher; Hathway, E. Abigail; Noakes, Catherine J.; Fitzgerald, Shaun

Abstract

We present a mathematical model and a statistical framework to estimate uncertainty in the number of SARS-CoV-2 genome copies deposited in the respiratory tract of a susceptible person, , over time in a well mixed indoor space.

By relating the predicted median for a reference scenario to other locations, a Relative Exposure Index (REI) is established that reduces the need to understand the infection dose probability but is nevertheless a function of space volume, viral emission rate, exposure time, occupant respiratory activity, and room ventilation. A 7 h day in a UK school classroom is used as a reference scenario because its geometry, building services, and occupancy have uniformity and are regulated.

The REI is used to highlight types of indoor space, respiratory activity, ventilation provision and other factors that increase the likelihood of far field ( m) exposure. The classroom reference scenario and an 8 h day in a 20 person office both have an and so are a suitable for comparison with other scenarios. A poorly ventilated classroom (1.2 l s−1 per person) has suggesting that ventilation should be monitored in classrooms to minimise far field aerosol exposure risk. Scenarios involving high aerobic activities or singing have ; a 1 h gym visit has a median , and the Skagit Choir superspreading event has .

Spaces with occupancy activities and exposure times comparable to those of the reference scenario must preserve the reference scenario volume flow rate as a minimum rate to achieve , irrespective of the number of occupants present.

Citation

Jones, B., Sharpe, P., Iddon, C., Hathway, E. A., Noakes, C. J., & Fitzgerald, S. (2021). Modelling uncertainty in the relative risk of exposure to the SARS-CoV-2 virus by airborne aerosol transmission in well mixed indoor air. Building and Environment, 191, 107617. https://doi.org/10.1016/j.buildenv.2021.107617

• Journal Article Type: Article
• Acceptance Date: Jan 9, 2021
• Online Publication Date: Jan 19, 2021
• Publication Date: 2021-03
• Deposit Date: Jan 22, 2021
• Publicly Available Date: Jan 20, 2022
• Journal: Building and Environment
• Print ISSN: 0360-1323
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 191
• Pages: 107617
• DOI: https://doi.org/10.1016/j.buildenv.2021.107617
• Keywords: Geography, Planning and Development; Environmental Engineering; Civil and Structural Engineering; Building and Construction
• Public URL: https://nottingham-repository.worktribe.com/output/5251345
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0360132321000305
• Additional Information: This article is maintained by: Elsevier; Article Title: Modelling uncertainty in the relative risk of exposure to the SARS-CoV-2 virus by airborne aerosol transmission in well mixed indoor air; Journal Title: Building and Environment; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.buildenv.2021.107617; Content Type: article; Copyright: © 2021 Elsevier Ltd. All rights reserved.