A barrier to COVID-19 in the workplace

During the COVID-19 pandemic, workplaces set up plexiglass barriers to prevent spread of the SARS-CoV-2 virus. These barriers are thought to block aerosol-sized droplets carrying the virus, which are expelled during coughs and other respiratory exhalations. But how well do they actually work?

Dhanak et al. found a plexiglass barrier that is 2.5 feet high and 3 feet wide blocks more than 80 percent of aerosolized droplets from a cough. However, a 12-inch-by-5-inch transactional opening at the bottom of a barrier significantly reduces this effectiveness to between 28 and 59 percent of aerosols.

The authors used a laser sheet to visualize the spread of aerosolized droplets containing a tracer fluid that were expelled by a simulated cough from a mannequin’s mouth. They supplemented this droplet visualization with particle count measurements.

The researchers also considered the effect of ambient airflow, which they demonstrated can dramatically alter aerosol dispersion. An ambient airflow going the opposite direction of a cough increased the effectiveness of a barrier with an opening at the bottom to over 99 percent.

“The results suggest that use of a plexiglass barrier in a room requires careful consideration of the ventilation in the room as well as the type and size of the barrier,” said author Manhar Dhanak. “For example, in the absence of proper ventilation, susceptible individuals who may be present behind the source of the cough may be adversely impacted.”

Next, the authors will extend this droplet visualization technique to examine how ventilation systems disperse cough aerosols around a room. This will allow them to identify features such as pockets of stagnant air where aerosol droplets might gather.

Source: “Effectiveness of plexiglass barriers in mitigating spread of aerosolized droplets in a cough,” by Manhar Dhanak, Adriana McKinney, Siddhartha Verma, and John Frankenfield, Physics of Fluids (2022). The article can be accessed at https://doi.org/10.1063/5.0129635 .

This paper is part of the Flow and the Virus Collection, learn more here .