Numerical model for cough‐generated droplet dispersion on moving escalator with multiple passengers

Abstract

The pandemic caused by the novel coronavirus COVID-19 is currently ongoing throughout the world, and careful measures are still required to curb significant loss of life and unprecedented economic loss. Fluid droplets expelled from infected individuals by respiratory events have attracted much attention in research because droplet transmission is considered to be one of the most critical mechanisms responsible for the rapid spread and continued circulation of infection among humans. 1 According to a recent study, airborne transmission is the main route for the spread of COVID-19. 2 Multiple studies on saliva droplets have demonstrated that thousands of virus-laden

Numerical Simulation of Droplet Dispersion and Passenger Infection Risk Assessment in a Subway Carriage

“…The dose-response model [58][59][60] is commonly used to assess the infection risk of humans. In this study, the model is applied to assess the infection risk among passengers in the carriage.…”

“…where α is a factor that accounts for the effect of the variant strain or vaccination, N is the total number of inhaled virions, and N 0 is the number of virus particles that lead to infection. According to the literature [60], α is set to 1. N 0 is a vital factor for calculating the probability of infection, and relevant studies have provided estimates of the value that vary between 100 and 1000 [61,62].…”

“…In this study, N 0 is fixed at 100. N is the number of viral particles that are trapped by each passenger's body and it is considered to present the amount of exposure to viral particles [60]. The calculation method for N is as shown in Equation (11).…”

“…λ v [63] is the viral load or virus density, and the value is 7 × 10 6 copies/mL. The parameter V 0 d is the total volume of droplets trapped by the passenger's body, and it is computed by using the droplet size at the time of its ejection from the mouth of the infected passenger rather than the volume after these droplets have evaporated [60]. This is because during the evaporation process, droplets only undergo changes in the volume of water within them, while the number of virus particles in the droplets remains constant.…”

“…This study employed the dose-response model [58][59][60] to calculate the exposure risk of passengers traveling with an infected passenger and compiled the number of passengers with different infection risks, as shown in Table 3. The statistical results revealed that the infection risk of passengers is closely linked to the initial conditions of the respiratory droplets released by the infected passenger, particularly the initial droplet size.…”