Evaluation of transmission risk of respiratory particles under different ventilation strategies in an elevator

People in elevators are at risk of respiratory infection because the elevator cabin is crowded and has poor ventilation. The exhaled particles may be inhaled by the susceptible person, deposited on the surface and suspended in the elevator, which can result in direct and indirect transmission. However, whether the air vent designs adopted in the elevator can effectively reduce the transmission risk of respiratory particles remains unknown. In this study, the dispersion of particles under four common ventilation strategies used in the commercial elevator was investigated by proven computational fluid dynamics (CFD) simulations. The flow field was simulated with the RNG k-ξ turbulence model and the Lagrangian method was adopted to track particle trajectories. The effects of air vent layout and airflow rate on particle transmission were analyzed. We found that more than 50% of exhaled particles (average value) were suspended in the cabin and difficult to discharge under the investigated ventilation strategies. The deposited fraction of particles on the susceptible person reached up to 39.14% for infiltration ventilation, which led to a high risk of contact infection. Increasing the ventilation rate could not significantly reduce the inhalation proportion of particles due to the poor airflow distribution inside the elevator. A more proper ventilation strategy should be explored for the elevator to control transmission risk.