Evaluating and mitigating the individual-to-individual transmission of breathing-released aerosol in a densely occupied classroom with impinging jet supply

作者：Chao Qin, Xueren Li, Hai Guo, Xiaopu Lyu · 发表于：Journal of Building Engineering · 年份：2025 · DOI：10.1016/j.jobe.2025.113715 · 被引用次数：3 · 研究领域：Infection Control and Ventilation、Noise Effects and Management、Building Energy and Comfort Optimization

Classrooms are featured by prolonged and dense occupancy, while the transmission risk of respiratory aerosols is usually evaluated based on several sources, or the aerosols in the entire space, ignoring the effects of individual-to-individual transmission in the crowd. We define the average concentration of the tracer gas (i.e., C i, av ) released by the i th individual in the head regions of other students to assess the risk for cross-transmission from the infected to others, and the crowd-averaged C i, av , (i.e., ) to evaluate the overall cross-transmission in the classroom. The impinging jet ventilation system is studied because it is promising for densely occupied spaces, while facing a drawback of recirculation airflow. Key findings reveal that increasing the supply velocity ( v s ) enhances the recirculation, disrupting thermal stratification at v s ≥ 1.5 m/s. While bulk indoor contaminant concentrations drop monotonically with the increase of v s . However, exhibits non-monotonic behavior: it declines from 6.56 ppm to 3.96 ppm as v s rises from 1.0 m/s to 2.0 m/s, but reaches a comparable low (4.20 ppm) at v s = 0.5 m/s. This demonstrates ’s superior sensitivity to interpersonal exposure risks compared to traditional spatially averaged metrics in crowded indoor spaces. Further analysis decouples the impacts of v s and supply airflow rate ( Q s ). As a result, increases with v s under a constant Q s , and drops as Q s rises under a constant v s . This study proposes de...