Shields at a restaurant in Placerville, Calif., in May 2020. Research suggests that transparent barriers can interfere with normal ventilation.Credit…Rich Pedroncelli/File, via The New York Times/Associated Press

It turns out plastic shields put up in classrooms to reduce COVID-19 spread likely don’t offer much benefit, interrupting airflow and increasing risk of exposure. Linsey Marr of Virginia Tech tells the New York Times, “One way to think about plastic barriers is that they are good for blocking things like spitballs but ineffective for things like cigarette smoke…the smoke simply drifts around them.” So while the barriers might block larger particles from coughs and sneezes, growing evidence suggests smaller aerosol particles waft around the barrier—putting others at risk for exposure. One expert says the plastic barriers shouldn’t stir alarm, but people should not assume they offer full protection either, and recommends face masks in addition to the barriers to lower risk of infection.