Tung C W, Mak C M, Niu J L, Hung K, Wu Yan, Tung Nam, Wong H M
Department of Building Services Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
School of Mechanical Engineering, Tongji University, China.
Build Environ. 2021 May 15;195:107760. doi: 10.1016/j.buildenv.2021.107760. Epub 2021 Mar 4.
Viable aerosols in the airflow may increase the risk of occupants contracting diseases. Natural ventilation is common in buildings and is accompanied by re-entry airflow during the ventilation process. If the re-entry airflow contains toxic or infectious species, it may cause potential harm to residents. One of the Covid-19 outbreaks occurred in a public residential building at Luk Chuen House (LC-House) in Hong Kong. It is highly suspected that the outbreak of the disease is related to the re-entry airflow. The study attempts to explain and discuss possible causes of the outbreak. In order to understand the impact of airflow on the outbreak, a public residential building similar to LC-House was used in the study. Two measurements M - I and M - II with the same settings were conducted for a sampling unit in the corridor under low and strong wind conditions respectively. The sampling unit and the tracer gas carbon dioxide (CO) were used to simulate the index unit and infectious contaminated airflow respectively. The CO concentrations of the unit and corridor were measured simultaneously. Two models of Traditional Single-zone model (TSZ-model) and New Dual-zone model (NDZ-model) were used in the analysis. By comparing the values obtained from the two models, it is indicated that the re-entry airflow of the unit is related to the corridor wind speeds and this provides a reasonable explanation for the outbreak in LC-House, and believes that the results can help understand the recent frequent cluster outbreaks in other residential buildings.
气流中的可存活气溶胶可能会增加居住者感染疾病的风险。自然通风在建筑物中很常见，并且在通风过程中伴随着回流气流。如果回流气流中含有有毒或传染性物质，可能会对居民造成潜在危害。香港绿村屋（LC-House）的一座公共住宅建筑发生了新冠肺炎疫情。人们高度怀疑该疾病的爆发与回流气流有关。该研究试图解释和讨论疫情爆发的可能原因。为了了解气流对疫情爆发的影响，研究中使用了一座与LC-House类似的公共住宅建筑。分别在低风速和强风速条件下，对走廊中的一个采样单元进行了两次设置相同的测量M-I和M-II。采样单元和示踪气体二氧化碳（CO）分别用于模拟指标单元和受感染的污染气流。同时测量该单元和走廊的CO浓度。分析中使用了传统单区模型（TSZ模型）和新双区模型（NDZ模型）两种模型。通过比较从这两种模型获得的值，表明该单元的回流气流与走廊风速有关，这为LC-House的疫情爆发提供了合理的解释，并认为该结果有助于理解近期其他住宅建筑中频繁出现的聚集性疫情。
