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

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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.