Wang Yongxin, Liu Zhijian, Liu Haiyang, Wu Minnan, He Junzhou, Cao Guoqing
Department of Power Engineering, North China Electric Power University, Baoding, Hebei, 071003, PR China.
Institute of Building Environment and Energy, China Academy of Building Research, Beijing, 100013, PR China.
Build Environ. 2022 Jul 1;219:109247. doi: 10.1016/j.buildenv.2022.109247. Epub 2022 May 30.
Negative pressure isolation wards could provide safety for health care workers (HCWs) and patients infected with SARS-CoV-2. However, respiratory behavior releases aerosols containing pathogens, resulting in a potential risk of infection for HCWs. In this study, the spatiotemporal distribution of droplet aerosols in a typical negative pressure isolation ward was investigated using a full-scale experiment. In this experiment, artificial saliva was used to simulate the breathing behavior, which can reflect the effect of evaporation on droplet aerosols. Moreover, numerical simulations were used to compare the transport of droplet aerosols released by the three respiratory behaviors (breathing, speaking, and coughing). The results showed that droplet aerosols generated by coughing and speaking can be removed and deposited more quickly. Because reduction in the suspension proportion per unit time was much higher than that in the case of breathing. Under the air supply inlets, there was significant aerosol deposition on the floor, while the breathing area possessed higher aerosol concentrations. The risk of aerosol resuspension and potential infection increased significantly when HCWs moved frequently to these areas. Finally, more than 20% of the droplet aerosols escaped from the ward when the number of suspended aerosols in the aerosol space was 1%.
负压隔离病房可为医护人员和感染新型冠状病毒的患者提供安全保障。然而，呼吸行为会释放含有病原体的气溶胶，从而给医护人员带来潜在的感染风险。在本研究中，通过全尺寸实验对典型负压隔离病房中飞沫气溶胶的时空分布进行了研究。在该实验中，使用人工唾液模拟呼吸行为，其能够反映蒸发对飞沫气溶胶的影响。此外，还利用数值模拟比较了三种呼吸行为（呼吸、说话和咳嗽）所释放的飞沫气溶胶的传播情况。结果表明，咳嗽和说话产生的飞沫气溶胶能够更快地被去除和沉积。因为单位时间内悬浮比例的降低幅度远高于呼吸情况。在送风入口下方，地面上有大量气溶胶沉积，而呼吸区域的气溶胶浓度较高。当医护人员频繁移动到这些区域时，气溶胶再悬浮和潜在感染的风险会显著增加。最后，当气溶胶空间中悬浮气溶胶数量为1%时，超过20%的飞沫气溶胶从病房逸出。
