Toilets dominate environmental detection of SARS-CoV-2 virus in a hospital

Zhen Ding; Hua Qian; Bin Xu; Ying Huang; Te Miao; Hui-Ling Yen; Shenglan Xiao; Lunbiao Cui; Xiaosong Wu; Wei Shao; Yan Song; Li Sha; Lian Zhou; Yan Xu; Baoli Zhu; Yuguo Li

We reviewed the design drawings of the building and its air-conditioning system, floor plans, and air-cleaning routes in the airborne infectious-disease zone. We conducted field measurements on 5 March in one of the identical wards on the fourth floor. We monitored the airflow direction through doorways and the bathroom door using smoke visualisation. In the area comprising the supply outlet, return inlet, and exhaust inlet in the bathroom, we measured the air speed using an anemometer (425, Testo, Germany), and recorded measurements as average values. We measured CO2 concentrations in the rooms, with four people present, using an indoor air-quality meter (IAQ-Calc 7515, TSI, USA) for 24 min. We investigated the airflow pattern in the room using incense smoke, with no patients present. Finally, we estimated the ventilation rates from the measured CO2 concentrations and air speeds.