University of Michigan - Ann Arbor

The authors propose a turbulent gas cloud hypothesis to explain long distance transmission of COVID-19. Recent transmission studies show that droplets are excreted in a turbulent gas cloud that contains air which traps clusters of droplets, varying in size. Within this warm, moist atmosphere, droplets remain airborne longer, extending their lifetime from less than a second to minutes, compared to isolated droplets. Droplets are dispersed further away from the infected person through forward cloud momentum, traveling up to 23-27 feet. The rate at which droplets settle or evaporate depend on their size, the turbulence and speed of the cloud, and environmental properties. Settled droplets contaminate surfaces as the cloud is propelled forward while other droplets evaporate, producing residue that remains suspended in the air for hours, depending on environmental surroundings. This turbulent gas cloud hypothesis is also supported by a recent report in China that found virus particles in ventilation systems.

Turbulent Gas Clouds and Respiratory Pathogen Emissions: New Model for Respiratory Emissions

Bourouiba, L. 2020. Turbulent Gas Clouds and Respiratory Pathogen Emissions. JAMA. 
doi:10.1001/jama.2020.4756

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