KYOTO Kyodo standing three steps apart on an escalator significantly reduces the risk of COVID 19 infection, while it is safer to descend than ascend one, according to a team at the Kyoto Institute of Technology.
The team lined up 10 maskless men, each 175 centimeters tall, on an escalator and computed the dispersion of droplets assuming that the man at the front coughed. The traced droplets measured less than 1.5 millimeters.
The research showed that droplets were quickly blown upward and traveled over the heads of others on a descending escalator.
On an ascending droplets fell to a level around the waist of the coughing man and remained in the air for a long time.
Masashi Yamakawa, professor at the Kyoto institute who led the team said it is important to keep a distance as human movements make the surrounding airflow unsteady and cause the dispersion of droplets. The dispersion of droplets would be reduced if they were worn properly, he said, although the study assumed that those riding the escalator did not wear masks.