Is Plexiglas keeping COVID-19 out? New Princeton study gives a clearer picture. Updated Dec 16, 2020; Wedged onto kindergarteners’ desks, professors’ lecterns and cashiers’ counters, Plexiglas barriers have become a ubiquitous COVID-19 precaution, nearly as pervasive as masks and hand sanitizer. But the jury’s still out on how effective they are in subduing the virus. In experiments showing how air particles can travel around the barriers, a research group led by Howard A. Stone, a professor of Mechanical & Aerospace Engineering at Princeton University, has been studying Plexiglas’s effect on virus transmission. Since April, Stone’s researchers have been studying airflows in speech and singing. For one project, they partnered with the Met Orchestra of New York, showing a singer’s airflow with an infrared camera, seen below.