Reducing aerosol transmission of SARS-CoV-2 in hospital elevators.

There is a worldwide discussion on the role of aerosols in the transmission of SARS‐CoV‐2. The WHO has recently highlighted the possible role of aerosols in the transmission of SARS‐CoV‐2. Aerosols containing small respirable particles are increasingly recognized as a potentially important mode of transmission of SARS‐CoV‐2. We investigate aerosol droplet persistence inside the confined space of hospital elevators and propose specific measures to reduce the associated risk of SARS‐CoV‐2 transmission. To investigate aerosol persistence in elevators, we mimic a single cough using a specially designed spray nozzle to disperse a controlled quantity of glycerol/ethanol droplets, that after evaporation of the ethanol have the same size distribution as evaporated respiratory droplets from a single cough. A SprayScan® laser sheet is used to detect aerosols that were placed in the back of the elevator at half‐height. Experiments were performed inside elevator cabins during normal operation with about 10%‐20% open door time. We found that it typically takes 12‐18 minutes before the number of aerosol particles decreased 100‐fold during normal operation of both medium‐ and large‐sized elevator cabins. With elevator doors permanently open, this time is reduced to 2‐4 minutes (Figure 1). In all cases, the number of aerosols decreases exponentially in time.