The assessment of personal exposure in restaurants considering heat sources and ventilation strategies

Outbreaks of airborne infections during meal consumption in diverse restaurant settings have been extensively reported. It is widely recognized that effective ventilation strategies are essential to minimize the infection risk in indoor environments, and these strategies should be tailored to the heat sources. The purpose of this study is to compare the spatial distribution of risk in restaurant rooms that use mixing or displacement ventilation, specifically focusing on the heat sources used for different food types, namely hotpot, normal Chinese food, and iced food. Computational Fluid Dynamics (CFD) was employed to assess exposure risk. Our results indicate that the use of low-temperature heat sources can elevate the risk of infection by increasing the local vertical temperature gradient. In comparison to no heat source, the risk increased by 190.9% and 99.6% for displacement and mixing ventilation strategies, respectively. Under mixing ventilation, both low-temperature and no heat sources showed lower infection risks when compared to displacement ventilation. However, displacement ventilation is found to be highly effective in reducing the risk of infection when using a high-temperature heat source, with only 12.3% of the infection risk observed in mixing ventilation. Furthermore, the use of displacement ventilation resulted in a significant reduction in the odors emitted by hotpot, which were instead absorbed by clothes in the mixing ventilation scenario. Our findings provide crucial insights into the development of appropriate ventilation strategies for reducing personal exposure to airborne infections in diverse restaurant settings. Specifically, we recommend using displacement ventilation in restaurants that utilize high-temperature heat sources, as it can substantially reduce the risk of infection.