Transmission of droplet aerosols in an elevator cabin: Effect of the ventilation mode

The recent outbreak of COVID-19 has threatened public health. Owing to the relatively sealed environment and poor ventilation in elevator cabins, passengers are at risk of respiratory tract infection. However, the distribution and dispersion of droplet aerosols in elevator cabins remain unclear. This study investigated the transmission of droplet aerosols exhaled by a source patient under three ventilation modes. Droplet aerosols produced by nose breathing and mouth coughing were resolved using computational fluid dynamics (CFD) simulations. We adopted the verified renormalization group (RNG) k-epsilon turbulence model to simulate the flow field and the Lagrangian method to track the droplet aerosols. In addition, the influence of the ventilation mode on droplet transmission was evaluated. The results showed that droplet aerosols gathered in the elevator cabin and were difficult to discharge under the mixed and displacement ventilation modes with specific initial conditions. The inhalation proportion of droplet aerosols for air curtain was 0.016%, which was significantly lower than that for mixed ventilation (0.049%) and displacement ventilation (0.071%). The air curtain confined the transmission of droplet aerosols with the minimum ratios of inhalation, deposition, and suspension and is thus recommended to reduce the exposure risk.

Automated summary

The recent COVID-19 outbreak poses a threat to public health. Due to the sealed and poorly ventilated environment, elevator cabins expose passengers to respiratory tract infections. This study examined the distribution and dispersion of droplet aerosols in elevator cabins and evaluated the transmission under three ventilation modes. Computational fluid dynamics simulations were used to analyze droplet aerosols produced by nose breathing and mouth coughing. The results showed that the air curtain ventilation mode significantly reduced the inhalation proportion of droplet aerosols compared to mixed and displacement ventilation modes, indicating its effectiveness in reducing exposure risk.