Airborne transmission of the delta variant of SARS-CoV-2 in an auditorium

Huang, Jianxiang, Hao, Tongping, Liu, Xiao, Jones, Phil ORCID: https://orcid.org/0000-0003-1559-8984, Ou, Cuiyun, Liang, Weihui and Liu, Fuqiang 2022. Airborne transmission of the delta variant of SARS-CoV-2 in an auditorium. Building and Environment 219 , 109212. 10.1016/j.buildenv.2022.109212

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Abstract

The Delta variant of SARS-CoV-2 has inflicted heavy burdens on healthcare systems globally, although direct evidence on the quantity of exhaled viral shedding from Delta cases is lacking. Literature remains inconclusive on whether existing public health guidance, formulated based on earlier evidence of COVID-19, should respond differently to more infectious viral strains. This paper describes a study on an outbreak of the Delta variant of COVID-19 in an auditorium, where one person contracted the virus from three asymptomatic index cases sitting in a different row. Field inspections were conducted on the configuration of seating, building and ventilation systems. Numerical simulation was conducted to retrospectively assess the exhaled viral emission, decay, airborne dispersion, with a modified Wells-Riley equation used to calculate the inhalation exposure and disease infection risks at the seat level. Results support the airborne disease transmission. The viral emission rate for Delta cases was estimated at 31 quanta per hour, 30 times higher than those of the original variant. The high quantity of viral plume exhaled by delta cases can create a risky zone nearby, which, for a mixing ventilation system, cannot be easily mitigated by raising mixing rates or introducing fresh air supply. Such risks can be reduced by wearing an N95 respirator, less so for social distancing. A displacement ventilation system, through which the air is supplied at the floor and returned from the ceiling, can reduce risks compared with a mixing system. The study has implications for ventilation guidelines and hygiene practices in light of more infectious viral strains of COVID-19.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Architecture
Additional Information:	License information from Publisher: LICENSE 1: Title: This article is under embargo with an end date yet to be finalised.
Publisher:	Elsevier
ISSN:	0360-1323
Date of First Compliant Deposit:	14 June 2022
Date of Acceptance:	16 May 2022
Last Modified:	06 Nov 2023 22:21
URI:	https://orca.cardiff.ac.uk/id/eprint/150254

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