For the first months of Covid-19, top health authorities pointed to larger droplets as the key transmission culprits, despite a chorus of protests from researchers like Allen. Tinier floating droplets can also spread the virus, they warned, meaning plastic shields can’t stop them. Not until
last month did the World Health Organization and U.S. Centers for Disease Control and Prevention fully affirm airborne transmission.
That meant plastic shielding had created “a false sense of security,” said building scientist Marwa Zaatari, a pandemic task force member of the American Society of Heating, Refrigerating and Air-Conditioning Engineers.
“Especially when we use it in offices or in schools specifically, plexiglass does not help,” Zaatari said. “If you have plexiglass, you’re still breathing the same shared air of another person.”
Recent CDC
research found that desk or table barriers in Georgia elementary schools didn’t correlate with lower infection rates. Mask mandates and ventilation improvements did.
An April
study published by the journal Science suggested that desk shields might even slightly raise the risk of Covid-like symptoms. And a prepublication
paper from Japan late last month linked plastic shielding with infections in a poorly ventilated office.
Such studies raise the ironic possibility that when venues install too much plastic and impede ventilation, they could be raising the very risk they’re trying to reduce.