Transport of Aerosols/Droplets Related to the Spread of COVID-19 in Indoor and Outdoor Environments

随着对如何最小化和控制新冠肺炎的知识的提高，艾伯塔省等许多地方正在逐步重新启动经济。这包括在不久的将来重新开放餐馆、公园和零售企业，以及学校。在公园、游泳池和海滩等许多地方都可以看到拥挤的景象。目前的2米社会距离很可能只来自大的呼吸道飞沫，而携带病毒的小气雾剂可以在空气中悬浮很长时间并传播很远的距离(例如，在最近的一项研究中，即使没有风，也可以达到7-8米)。鉴于新冠肺炎病毒可以在气溶胶中持续感染数小时，而感染可能只由一种病毒引起，因此研究小型气溶胶的传输是势在必行的。公共卫生政策制定者具体面临以下紧迫问题：(A)在不同的室内和室外条件下，呼吸性气雾剂/飞沫的运输风险是什么？(B)当地特定气候对运输有何影响？以及(C)对于在这种情况下聚集的人，应制定何种公共政策？ 本研究将为回答这些问题提供科学依据。具体地说，本研究将利用计算流体力学模型，重点研究在不同的室内(供暖、通风和空调)和室外(风速和风向)条件下，在采取预防措施(塑料屏蔽物)的情况下，说话、唱歌、咳嗽和打喷嚏所产生的液滴/气溶胶的传输。这项研究还将评估各种社交聚会场景下新冠肺炎的传播风险，并根据建模结果提出潜在的政府政策建议。预计这项研究将对艾伯塔省健康和其他方面在更新/制定有效政策以阻止新冠肺炎传播、指导新冠肺炎限制的放松以及更好地为加拿大人应对未来潜在的下一波新冠肺炎或类似流行病做好准备方面产生重大影响。

With the improving knowledge of how to minimize and control of COVID-19, many places such as Alberta are gradually relaunching the economy. This includes re-opening restaurants, parks and retail businesses, as well as schools in the near future. Crowding has been seen in many places such as parks, swimming pools and beaches. The current 2 m social distancing is likely only derived for large respiratory droplets, while virus-laden small aerosols can be suspended in air for a long time and travel large distances (e.g., 7-8 m even without wind in a recent study). Given that COVID-19 virus can remain infective for hours in aerosols and infection can be caused just by one virus, it is imperative to study the transport of small aerosols. Public health policy makers are specifically facing the following urgent questions (a) what are the transport risks of respiratory aerosols/droplets in different indoor and outdoor conditions? (b) what are the impacts of local specific climate on the transport? And (c) what public policy should be made on people gathering in these conditions? This research will provide the scientific foundation to answer these questions. Specifically, this research will focus on the transport of droplets/aerosols generated by talking, singing, coughing, and sneezing in different indoor (heating, ventilation, and air conditioning) and outdoor (wind speed and direction) conditions and with preventive measures (plastic shields), using computational fluid dynamics modeling. The research will also assess the spreading risks of COVID-19 under various social gathering scenarios and suggest potential government policies, based on the modeling results. This research is expected to have a significant impact to Alberta Health and others in updating/making effective policies in stopping the spread of COVID-19, guiding the relaxation of COVID-19 restrictions, and better preparing Canadians for the potential next wave of COVID-19 or similar pandemics in the future.