Evaluation of inhalation and touching risks in a moving elevator car based on the airborne transmission of droplet nuclei

Abstract

It is necessary to explore the effects of airflow in moving elevator cars on the diffusion of droplet nuclei and evaluate inhalation and touching risks due to the elevator car being a place where dangerous respiratory diseases can spread. A realizable k–ε turbulence model and discrete phase model were applied with gas–solid multiphase modeling principles to simulate the diffusion of droplet nuclei generated by coughs in a moving elevator. Four cases are discussed with differences in the elevator motion direction and air supply system. The results show that the elevator movement causes the airflow direction in respiratory regions to change by more than 30°, which is more evident in the absence of air supply. Under the combined effects of the airflow supply and the thermal plume, the high-temperature zone became a gathering point for droplet nuclei. The upward elevator movement increases the inhalation risk of a passenger who stands farther from an index patient and has the highest inhalation risk about 4.4 × 10−19. The downward movement increases the duration to about 40 s, for which that passenger remains at the highest risk. The area in front of the patient is the highest touching risk area, especially for downward motion. In addition, the button area is a high-risk area for touching because about 4% of cough droplet nuclei are deposited there. This may spread viable viruses if passengers touch the buttons, even if the coughing person is no longer in the elevator. Thus, elevator cars need to be regularly disinfected, especially the button area.