Hong Kong Med J 2008;14(Suppl 5):S19-22
Transport phenomena of human exhaled droplets due to respiratory action in ventilated indoor environments
C Chao
Department of Mechanical Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong
1. The transport dynamics of expiratory droplets was modelled and verified against experimental data.
2. Droplet size distributions in air were measured. Small droplets (initial size ≤45 µm) were largely airborne. Large droplets (initial size ≥87.5 _m) settled quickly.
3. The transport characteristics of expiratory droplets were highly influenced by ventilation airflow patterns. The location of the exhaust vent can play a significant role in controlling the dispersion pattern of expiratory droplets.
4. Deviations from the perfectly mixed condition were found. Further development of risk assessment models taking imperfect mixing conditions into account are needed.
2. Droplet size distributions in air were measured. Small droplets (initial size ≤45 µm) were largely airborne. Large droplets (initial size ≥87.5 _m) settled quickly.
3. The transport characteristics of expiratory droplets were highly influenced by ventilation airflow patterns. The location of the exhaust vent can play a significant role in controlling the dispersion pattern of expiratory droplets.
4. Deviations from the perfectly mixed condition were found. Further development of risk assessment models taking imperfect mixing conditions into account are needed.