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. But is the distance enough to help avoid infectious aerosols?
Not indoors, say researchers in the Penn State Department of Architectural Engineering. The team found that indoor distances of two meters — about six and a half feet — may not be enough to sufficiently prevent transmission of airborne aerosols. Their results were made available online ahead of the October print edition of Sustainable Cities and Society.
“We set out to explore the airborne transport of virus-laden particles released from infected people in buildings,” said Gen Pei, first author and doctoral student in architectural engineering at Penn State. “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 employed 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,” said Donghyun Rim, corresponding author and 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 aerosols traveled farther and more quickly in rooms with displ