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

In the second stage, the air change rate was measured using the tracer decay method, which involved the release of a tracer gas into the restaurant that subsequently mixed the flow from with 10 desk fans. We measured the tracer concentration at three points in the room. The elevator and fire door were used every two minutes to mimic the traffic that was observed in the recording of the January 24 lunch, with the fire door closing automatically after a period of 3 s. We identified an exhaust flow through the doorway of the restroom and that bidirectional air exchange occurred through the opening and closing of the fire door. The non-operating exhaust fans were sealed relatively well, with nearly negligible air flow. After the measurements, we assigned the health status (ill vs. healthy) of each person at non-A tables as the dependent variable and applied a binary logistic regression model to investigate the association between the measured concentrations of trace gas and infection probability.