Monitoring and Modelling the Impact of Ventilation On The Long-Range Exposure Risk to SARS-CoV-2 Laden Aerosols in Restaurants

Abstract

The UK Government’s Events Research Programme (ERP) aimed to examine the risk of transmission of SARS-CoV-2 at large-scale entertainment events and to explore ways to enable people to attend them safely. It was the largest programme of its kind worldwide.The transmission of the SARS-CoV-2 virus is thought to be primarily via the inhalation of airborne respiratory droplets and aerosols both at close and long range. Building ventilation can reduce the long range inhaled dose, thus the environmental study of the ERP undertook a field study of indoor air quality to evaluate ventilation provision at several large venues during multiple live events. Measured CO2 concentrations at 14 events taking place across 12 restaurants of two large event stadia in the UK, indicate that they were generally well ventilated, and were < 1000 ppm on averageIndividual and population-based risk models show the personal risk in all the restaurants is found to be lower than for the reference scenario, 8 hours in a 20-person office. However, the probability of the presence of infected people and the number of the susceptible people increases with the number of occupants, so population level risks of transmission due to attending restaurants at these events are higher than the reference case and would be dependent upon the occupancy, exposure time and prevalence of COVID-19 in the community at the time.Future measures to mitigate against long range transmission in restaurant scenarios include both reducing occupancy density, exposure time, and introducing equivalent ventilation to poorly ventilated venues.

Keywords: hospitality, COVID-19, SARS-COV-2, Ventilation, Airborne transmission, Aerosols