Abstract View
Influence of Wind and Relative Humidity on the Social Distancing Effectiveness to Prevent COVID-19 Airborne Transmission: A CFD Study
YU FENG, Thierry Marchal, Ted Sperry, Hang Yi, Oklahoma State University
Abstract Number: 7
Working Group: The Role of Aerosol Science in the Understanding of the Spread and Control of COVID-19 and Other Infectious Diseases
Abstract
The ongoing pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has illustrated the global public health threat. It has been confirmed that the coronavirus disease 2019 can be transmitted through droplets created when an infected human coughs or sneezes. Accordingly, 6-feet social distancing has been advised to reduce the spread of the disease among humans. However, it is unknown whether 6 feet are sufficiently far or not. To provide evidence and insight into the “social distancing” guidelines, a validated computational fluid-particle dynamics (CFPD) model was employed to simulate the transient transport, condensation/evaporation, and deposition of SARS-CoV-2 laden droplets emitted by a cough or sneeze between two virtual humans with different environmental wind velocities. Initial droplet diameters range from 2 to 2000 microns, and the wind velocities range from 0 to 16 km/h, representing different wind forces from calm to gentle. Ambient relative humidities are 40% and 99.5%. Trajectories of SARC-CoV-2-laden droplets are visualized. Numerical results show that most of the large droplets fall to the ground in 6 feet. However, micro-droplets can suspend in the air much longer, causing a potential health risk to nearby people. HighER relative humidity will reduce the transmission distances of the virus-laden droplets due to less droplet evaporation effects. The 6-feet social distancing policy is not sufficient to protect the inter-person aerosol transmission, since the suspending micro-droplets were influenced by the convection effect and transport from the human who coughs/sneezes to the other human in less than 5 seconds. Thus, due to the complex real-world environmental ventilation conditions, a social distance longer than 6 feet needs to be considered. Wearing masks should be also recommended for both infected and healthy humans.