Due to outbreaks of respiratory disease, the control and prevention strategy of respiratory disease transmission has become a global issue and concern. In indoor environments, a healthy person (HP) has a high possibility to be infected when facing expiratory droplets from an infected person (IP) during close contacts. This work investigated experimentally bioaerosol deposition and inhalation by the HP and the control of disease transmission by using personalized ventilation (PV) during close contact. Two thermal manikins were used to represent the HP and IP. A PV system was designed and built. Benign Escherichia coli and bacteriophage were used to represent the bacterial and viral pathogens in expiratory droplets, respectively. Firstly, the effect of distance between the PV and the HP on exposure of the HP to airborne droplets from the IP in different orientations was studied. With a short distance between the HP and the PV, both constant and dynamic PV airflow patterns effectively reduced personal exposure of the HP. Secondly, bioaerosol deposition and inhalation by the HP and the effect of PV on the HP were investigated. By optimizing the velocity of PV flow with respect to the distance between the HP and IP, the bioaerosol deposited on the HP’s face, body, and inhaled could be reduced by around 98%, 85% and 100%, respectively. Thirdly, the effect of head orientations of the IP and the performance of PV on bioaerosol deposition on the HP during close contact was studied. Different orientations of the IP's head resulted in significantly different effects on deposition on the HP. PV flow reduced the bioaerosol deposition on the HP for most cases and the reduction was between 51.7% and 94.5% compared to each case without PV. The results show that during close contact PV is an effective method to control the droplet spray on the mucous membranes, droplet deposition, and inhalation by the exposed person.
(Supervisor: Prof. Huihe Qiu and Prof. Christopher YH Chao)