Clear plastic barriers have become a staple in many public settings amid the pandemic, but scientists say they often do little to prevent COVID-19's spread, and at times, may actually make things worse, The New York Times reported Aug. 19.
The plastic shields are intended to protect people from germs in public settings such as classrooms, offices or stores. However, researchers who study aerosols and ventilation say the barriers can impede normal air flow and create "dead zones" where aerosol particles accumulate in high concentrations, preventing clean air from cycling back into a room.
"If you have a forest of barriers in a classroom, it's going to interfere with proper ventilation of that room," Linsey Marr, PhD, professor of civil and environmental engineering at Blacksburg-based Virginia Tech and a leading expert on viral transmission, told the Times. "Everybody's aerosols are going to be trapped and stuck there and building up, and they will end up spreading beyond your own desk."
There is little real-world evidence available on how the clear barriers affect the risk of contracting COVID-19, but preliminary studies suggest they offer limited protection, according to the Times. For example, modeling studies done by British researchers found the plastic shields effectively blocked large particles from someone coughing, but not smaller aerosols exhaled while someone speaks.
"Smaller aerosols travel over the screen and become mixed in the room air within about five minutes,” Catherine Noakes, PhD, a ventilation expert and professor of environmental engineering for buildings at the University of Leeds in England, told the Times. "This means if people are interacting for more than a few minutes, they would likely be exposed to the virus regardless of the screen."
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