Airborne transmission of pathogen-laden expiratory droplets in open outdoor space

Virus-laden droplets dispersion may induce transmissions of respiratory infectious diseases. Existing research mainly focuses on indoor droplet dispersion, but the mechanism its and exposure in outdoor environment is unclear. By conducting CFD simulations, this paper investigates evaporation transport solid-liquid an open environment. Droplet initial sizes (dp = 10 μm, 50 100 μm), background relative humidity (RH 35%, 95%), wind speed (Uref 3 m/s, 0.2 m/s) social distances between two people (D 0.5 m, 1 1.5 5 m) are investigated. Results show that thermal body plume destroyed when m/s (Froude number Fr ~ 10). The inhalation fraction (IF) susceptible person decreases exponentially distance (D) increases from m to m. exponential decay rate (b) ranges 0.93 1.06 (IF=IF0e-b(D-0.5)) determined by diameter humidity. Under weak 0.01), upward significantly influences which similar with space. Droplets μm disperse upwards while most fall down ground due larger gravity force. Interestingly, deposition ten times higher at Uref than m/s. Thus, a high does not necessarily lead smaller risk if locating downwind region infected person, outdoors suggested only keep greater each other also stand considerable angles prevailing direction.