Experimental Investigation of Aerosol and CO₂ Dispersion for Evaluation of COVID-19 Infection Risk in a Concert Hall

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 (δ) close to 0.3 µm and a horizontal initial particle velocity (vp,x) 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 vg,z=0.05 m/s 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.