Computational study on the transmission of the SARS-CoV-2 virus through aerosol in an elevator cabin: Effect of the ventilation system

Abstract

Aerosol transmission is now well-established as a route in the spread of the SARS-CoV-2 virus. Factors influencing the transport of virus-laden particles in an elevator cabin are investigated computationally and include human respiratory events, locations of the infected person(s), and the ventilation system (ventilation mode, ventilation capacity, and vent schemes). “Breath,” “cough,” and “sneeze” are defined quantitatively by the fluid jet velocities and particle sizes. For natural ventilation, most particles exhaled by sneezing and coughing tend to deposit on surfaces quickly, but aerosol generated by breathing will remain suspended in the air longer. For forced ventilation, motions of particles under different ventilation capacities are compared. Larger particles otherwise deposited readily on solid surfaces may be slowed down by airflow. Air currents also accelerate the motions of smaller particles, facilitating the subsequent deposition of micrometer or sub-micrometer particles. Locations of the infected person(s) lead to different spreading scenarios due to the distinctive motions of the particles generated by the various respiratory events. Sneeze particles will likely contaminate the person in front of the infected passenger only. Cough particles will increase the risk of all the people around the injector. Breath particles tend to spread throughout the confined environment. An optimized vent scheme is introduced and can reduce particles suspended in the air by up to 80% as compared with commonly used schemes. The purification function of this vent model is robust to various positions of the infected passenger.

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

“…The results reveal that the ventilation mode can significantly affect the dispersion of droplet aerosols in the elevator cabin. Owing to poor ventilation in the current ventilation mode, the exposure risk of droplet aerosols in elevator cabins may be higher than that in other indoor environments [ 20 ]. Thus, it is urgently necessary to explore more appropriate ventilation strategies to control the spread of respiratory infectious diseases [ 20 , 25 ].…”

“…Owing to poor ventilation in the current ventilation mode, the exposure risk of droplet aerosols in elevator cabins may be higher than that in other indoor environments [ 20 ]. Thus, it is urgently necessary to explore more appropriate ventilation strategies to control the spread of respiratory infectious diseases [ 20 , 25 ]. The AC ventilation mode can effectively decrease interpersonal exposure between passengers and is thus recommended for use in elevators.…”

“…Previous studies investigated the spread of droplet aerosols in various indoor environments, such as fever clinics [ 17 ], operating rooms [ 18 ], and coach buses [ 19 ]. It was found that droplets smaller than 30 μm were almost unaffected by gravity and inertia, and droplet transport was mainly affected by the indoor flow field [ 20 , 21 ]. Effective ventilation is thus the key to controlling airborne transmission of respiratory infectious diseases.…”

Optimal position of air purifiers in elevator cabins for the improvement of their ventilation effectiveness

“…Under certain operating conditions, the cabins can become reservoirs of viral loads acting as transmission sources [4–8] [ [4] , [5] , [6] , [7] , [8] ]. Hence, the incorporation of additional ventilation systems in the cabins is an ideal solution to guarantee the safety of users [ 9 , 10 ].…”

Natural Ventilation and Aerosol Particles Dispersion Indoors

“…Pourfattah et al [26] conducted a state-of-the-art review on the challenges in modelling and simulation of minimal particle dispersion such as airborne viruses or aerosols. Furthermore, researchers investigated the effect of natural ventilation and air circulation on various different scenarios of indoor airborne virus transmission [10,[27][28][29][30], including the effect of air purifiers [10]. Park et al 2021 [31] proposed natural ventilation strategies to prevent coronavirus transmission inside a school building.…”