Evaluation of airborne particle exposure for riding elevators.

Social distancing is a key factor for health during the COVID-19 pandemic. In many indoor spaces, such as elevators, it is difficult to maintain social distancing. This investigation used computational-fluid-dynamics (CFD) to study airborne particle exposure in riding an elevator in a typical building with 35 floors. The elevator traveled from the ground floor to the 35th floor with two stops on floor 10 and floor 20, comprising 114 s. The CFD simulated the dispersion of the aerosolized particles exhaled by an index person while breathing in both lobby and elevator areas. The study calculated the accumulated dose of susceptible riders riding in elevators with the index person under different conditions including different ventilation rates, air supply methods, and elevator cab geometries. This investigation also studied a case with a single cough from the index person as the person entered the elevator. The results show that, due to the short duration of the average elevator ride, the number of particles inhaled by a susceptible rider was low. For the reference case with a 72 ACH (air changes per hour) ventilation rate, the highest accumulated particle dose by a susceptible passenger close to the index person was only 1.59. The cough would cause other riders to inhale approximately 8 orders of magnitude higher particle mass than from continuous breathing by the index person for the whole duration of the ride.