Two Stages Exposure of Co-Occupants to Respiratory Events Indoors: Numerical Results

Jianlei Niu and Xiaoping Li


Personal exposure, ventilation system, numerical simulation, respiratory droplets, infection transmission


Infection transmission indoors has become one of the major concerns since the outbreaks of SARS in 2003. Ventilation method possesses strong influences on the airflow patterns and consequently affects the spread of some infectious respiratory diseases. It will be important to understand whether the three typical air distribution schemes can have significant differences in reducing the infections between occupants in a room. Meanwhile, mouth covering is one feasible measure to mitigate viral infection and has been extensively studied. However, its performance in reducing airborne infections under different ventilation conditions was seldom investigated. In this paper, numerical methods are adopted to investigate the co-occupant’s exposure under different ventilation systems when the infected person coughs directly or with the mouth covered. The preliminary results indicate that the whole exposure can be roughly separated as two stages, a first direct exposure stage due to high momentum coughing jet and a later indirect exposure stage because of indoor air movement. Stratified ventilation system can not ensure the better inhaled air quality for the co-occupant, while displacement ventilation (DV) can achieve the lowest personal exposure if the infected person covers the mouth when coughing.

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