A new possible route of airborne transmission caused by the use of a physical partition

This study experimentally examines the effect of a physical partition on the risk of short-distance cross-infection in a densely occupied canteen. A human subject was employed to simulate an infected person and three thermal manikins were used to simulate the exposed persons, who sat around the same dining table. Four influential factors were examined, including the height and the type of physical partition (i.e., cross-partition and linear-partition), and the head posture and the activity (i.e., dining or not) of the infected person. The CO2 exhaled by the subject was used to simulate the exhaled air. The ratio of the CO2 concentration at the monitoring points to the background CO2 concentration in the canteen was defined as the exposure index. A partition that is not lower than the breathing level of the infected person by 3–5 cm can effectively block the horizontal development of the expiratory jet. Compared with no partition, the use of cross-partition and linear-partition results in an increase of the exposure index in the source compartment (i.e., the area facing the subject) by 97.2% and 25.5%, respectively. It takes, on average, 11 min for the CO2 concentration in the source compartment to decay back to the background concentration, after the subject completes dining and leaves the seat. This implies that a latter diner is possibly exposed to the high concentration of the expiratory air released by the former diner, presenting a new possible transmission route. The findings obtained in this study should contribute to an improved design and application of physical partitions.