Abstract
The dispersion of small aerosols in a concert hall is experimentally studied for estimating the risk of infection with SARS-CoV-2 during a concert. A mannequin was modified to emit an air stream containing aerosols and CO2. The aerosols have a size distribution with a peak diameter close to 0.3 µm and a horizontal initial particle velocity () of 2.4 m/s. The CO2-concentration (c) emitted simultaneously is 7500 ppm. It is investigated, if the spatial dissipation of aerosols and CO2 can be correlated. This would allow the use of technically easier CO2 measurements to monitor compliance with aerosol concentration limits. Both aerosol and CO2 concentrations are mapped by different sensors placed around the mannequin. As a result, no significant enrichment of aerosols and CO2 was obtained outside a radius of 1.5 m when the fresh air ventilation in the concert hall has a steady vertical flow with a velocity of and the installed ventilation system was operating at an air change rate per hour (ACH) of 3, corresponding to an air exchange rate of 51,000 m3/h. A Pearson correlation coefficient of 0.77 was obtained for CO2 and aerosol concentrations measured simultaneously at different positions within the concert hall.
Highlights
Very recently, the role of aerosols in the transmission of SARS-CoV-2 has been pointed out by several papers [1,2,3,4,5,6]
Our experimental concept presented in this paper enables assessment of infection risk for audience in a concert hall based on experimental data representing the specific situation of the indoor environment under investigation
The results indicate that at 1.5 m distance from a potential emitter of aerosols with a diameter of 0.3 μm the aerosol air flow is entrained to the ceiling by the fresh air ventilation system when the vertical air flow is at least v g,z = 0.05 m/s
Summary
The role of aerosols in the transmission of SARS-CoV-2 has been pointed out by several papers [1,2,3,4,5,6]. The spatial distribution of aerosols in an indoor environment is mostly derived from numerical simulation [7,8,9]. For public spaces such as concert halls, theaters, or event facilities such data are almost unknown and to date no experimental investigation of aerosol dispersion is reported for such spaces in literature. The availability of such data is important in understanding the COVID-19 risk assessment. In the present paper experiments have been performed to get more detailed understanding of the spatial distribution of aerosols in a concert hall. Humans emit respiratory droplets ranging from 0.1 to several tens of micrometers in diameter depending on respiratory activities such as breathing, speaking, or sneezing [10,11,12,13]
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