Evidence for probable aerosol transmission of SARS-CoV-2 in a poorly ventilated restaurant

Yuguo Li; Hua Qian; Jian Hang; Xuguang Chen; Ling Hong; Peng Liang; Jiansen Li; Shenglan Xiao; Jianjian Wei; Li Liu; Min Kang

The tracer gas measurement consisted of two stages. In the first stage, we released ethane gas through an 8-mm inner diameter pipe at a speed of 1.5 m/s at 32-34 °C, with the pipe outlet placed immediately above the index patient's nose. This mode of release mimicked the index patient (assumed to be A1) talking and moving their head around. Tracer gas is known to be an effective surrogate for modelling the spread of fine droplets or droplet nuclei (Bivolarova et al., 2017) . In the first of two experiments, we monitored the gas concentrations at 14 points, namely all of the chairs where the infected persons of families B and C had sat ( Figure S3 ). In the second experiment, gas concentrations were only monitored at seven points, owing to the time required for rotational sampling at each point.