Effectiveness of personalized air curtain in reducing exposure to airborne cough droplets

To minimize infection risk of airborne transmission during close contact, a personalized air curtain (PAC) system was proposed to protect users from airborne droplets. This work investigated the performance of PAC in reducing exposure to airborne droplets through two thermal manikins in close proximity (0.82 m). A cough generator was put into one of the manikins (an infected person) to release cough droplets to simulate coughing activities. Concentration of airborne droplets in the inhalation zone of the other manikin, as a healthy person (HP), was measured. The effect of PAC with different flow rates (from 9 L/s to 27 L/s) and distances to the HP (15 cm–65 cm) on exposure to airborne droplets was investigated. The performance of PAC was further compared with that of personalized ventilation (PV), integrated PAC-PV, and partitions. Visualization experiments were performed to observe the interaction between the cough jet and PAC, PV, PAC-PV, and partitions. The results showed that exposure reduction caused by PAC was from 42% to 87% considering the flow rate and distance between HP and PAC. When the PAC velocity increased to ‘critical velocity’, i.e., 5 m/s, the exposure reduction was nearly stable and the distance between PAC and HP has almost no influence on the exposure reduction. Besides, exposure reduction of integrated PAC-PV was between 94% and 98%, showing a quite good performance in reducing airborne droplets. The results indicated that PAC and PAC-PV could be used as mitigation measures to protect users and reduce exposure to airborne droplets.