Indoor distances of two meters—about six and a half feet—may not be enough to sufficiently prevent transmission of airborne aerosols, researchers report.

Eighteen months ago, stickers began to dot the floors of most shops, spaced about six feet apart, indicating the physical distance required to avoid the COVID-19 virus an infected person may shed when breathing or speaking.

“We set out to explore the airborne transport of virus-laden particles released from infected people in buildings,” says Gen Pei, a doctoral student in architectural engineering at Penn State and first author of the paper, published in Sustainable Cities and Society.

“We investigated the effects of building ventilation and physical distancing as control strategies for indoor exposure to airborne viruses.”

The researchers examined three factors: the amount and rate of air ventilated through a space, the indoor airflow pattern associated with different ventilation strategies, and the aerosol emission mode of breathing versus talking. They also compared transport of tracer gas, typically used to test leaks in air-tight systems, and human respiratory aerosols ranging in size from one to 10 micrometers. Aerosols in this range can carry SARS-CoV-2.

“Our study results reveal that virus-laden particles from an infected person’s talking—without a mask—can quickly travel to another person’s breathing zone within one minute, even with a distance of two meters,” says corresponding author Donghyun Rim, an associate professor of architectural engineering.

“This trend is pronounced in rooms without sufficient ventilation. The results suggest that physical distance alone is not enough to prevent human exposure to exhaled aerosols and should be implemented with other control strategies such as masking and adequate ventilation.”

The researchers found that airborne aerosols traveled farther and more quickly in rooms with displacement ventilation, where fresh air continuously flows from the floor and pushes old air to an exhaust vent near the ceiling.

Read the full article about social distancing by Ashley WennersHerron at Futurity.