Role of pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-19 outbreak in a coach bus.
Role of pathogen-laden expiratory droplet dispersion and natural ventilation explaining a COVID-19 outbreak in a coach bus.
复制标题
载有病原体的呼气飞沫扩散和自然通风的作用解释了长途客车中 COVID-19 的爆发
DOI：
10.1016/j.buildenv.2022.109160
复制
发表时间：
2022-07-15
影响因子：
7.4
通讯作者：
Fan, Xiaodan
中科院分区：
文献类型：
--
作者：
Luo, Qiqi;Ou, Cuiyun;Hang, Jian;Luo, Zhiwen;Yang, Hongyu;Yang, Xia;Zhang, Xuelin;Li, Yuguo;Fan, Xiaodan
关键词：
公交车内飞沫传播对呼吸道疾病感染风险的影响机制尚不清楚。基于在公共汽车尾部有一名指示患者的一次感染七次COVID-19爆发的实验，我们进行了CFD模拟，以研究初始液滴直径的综合影响（示踪气体，5 μm、50 μm和100 μm），每小时自然换气率（ACH = 0.62、2.27和5.66 h−1，与公交车速度有关）和相对湿度（RH = 35%和95%）对携带病原体的飞沫扩散和感染风险的影响。客车车外表面的压差导致自然通风气流从车后天窗进入，从车前天窗离开。当ACH = 0.62 h-1（怠速状态）时，示踪气体的30 min暴露感染风险（TIR）为15.3%（公共汽车后部）-11.1%（公共汽车前部），并且在ACH = 5.66 h-1（高公共汽车速度）时降低到3.1%（公共汽车后部）-1.3%（公共汽车前部）。100 μm/50 μm）几乎与ACH无关，峰值（≤ 3.1%）接近索引患者，因为超过99.5%/97.0%的液滴存款由于重力而局部沉积。随着通风量的增加，5 μm粒径的液滴可以进一步分散。然而，ACH = 5.66 h−1时，5 μm液滴的TIR对于后排乘客来说相对较小（最大0.4%），在公交车中部和前部甚至更小（<0.1%）。本研究验证了与一般房间不同的是，大多数5 μm的水滴存款在通过具有大面积表面的狭长巴士空间（L = 11.4 m）的路线上。因此，示踪气体只能模拟微小的液滴，沉积量很小，但不能取代5-100 μm的液滴分散在客车上。
The influencing mechanism of droplet transmissions inside crowded and poorly ventilated buses on infection risks of respiratory diseases is still unclear. Based on experiments of one-infecting-seven COVID-19 outbreak with an index patient at bus rear, we conducted CFD simulations to investigate integrated effects of initial droplet diameters(tracer gas, 5 μm, 50 μm and 100 μm), natural air change rates per hour(ACH = 0.62, 2.27 and 5.66 h−1 related to bus speeds) and relative humidity(RH = 35% and 95%) on pathogen-laden droplet dispersion and infection risks. Outdoor pressure difference around bus surfaces introduces natural ventilation airflow entering from bus-rear skylight and leaving from the front one. When ACH = 0.62 h−1(idling state), the 30-min-exposure infection risk(TIR) of tracer gas is 15.3%(bus rear) - 11.1%(bus front), and decreases to 3.1%(bus rear)-1.3%(bus front) under ACH = 5.66 h−1(high bus speed).The TIR of large droplets(i.e., 100 μm/50 μm) is almost independent of ACH, with a peak value(∼3.1%) near the index patient, because over 99.5%/97.0% of droplets deposit locally due to gravity. Moreover, 5 μm droplets can disperse further with the increasing ventilation. However, TIR for 5 μm droplets at ACH = 5.66 h−1 stays relatively small for rear passengers(maximum 0.4%), and is even smaller in the bus middle and front(<0.1%). This study verifies that differing from general rooms, most 5 μm droplets deposit on the route through the long-and-narrow bus space with large-area surfaces(L∼11.4 m). Therefore, tracer gas can only simulate fine droplet with little deposition but cannot replace 5–100 μm droplet dispersion in coach buses.
登录
查看更多内容
影响因子：
5.8
作者：
Liu, L.;Li, Y.;Jensen, R. L.
通讯作者：
Jensen, R. L.
影响因子：
4
作者：
Duan, Wenzhu;Mei, Dan;Hou, Shanshan
通讯作者：
Hou, Shanshan
影响因子：
--
作者：
Cermak, Radim;Melikov, Arsen K.
通讯作者：
Melikov, Arsen K.
影响因子：
13.6
作者：
Chen W;Qian H;Zhang N;Liu F;Liu L;Li Y
通讯作者：
Li Y
环境湿度对呼出呼吸液滴蒸发和分散的影响：数值研究
影响因子：
4.5
作者：
Ji, Yichen;Qian, Hua;Zheng, Xiaohong
通讯作者：
Zheng, Xiaohong