COVID-19 IS TRANSMITTED THROUGH AEROSOLS. WE HAVE ENOUGH EVIDENCE, NOW IT IS TIME TO ACT.

Many months into the COVID-19 pandemic, the coronavirus is still spreading uncontrolled through the U.S. Public health authorities including the U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) tell us to remain six feet apart, wash our hands, disinfect frequently touched surfaces, and wear masks. But compliance with these measures—especially masks—is mixed, and daily we hear of cases where people do not know how they were infected. We hear about superspreading events, where one person infects many, happening in crowded bars and family gatherings, but not at outdoor demonstrations. Beaches in cities like Chicago are closed, but gyms and indoor dining at restaurants have reopened. It is no wonder the public is confused.

a group of people walking in front of a crowd: People wear protective face masks while shopping at the Union Square Greenmarket during Phase 4 of re-opening following restrictions imposed to slow the spread of coronavirus on Aug. 22, 2020 in New York City.© Noam Galai—Getty Images People wear protective face masks while shopping at the Union Square Greenmarket during Phase 4 of re-opening following restrictions imposed to slow the spread of coronavirus on Aug. 22, 2020 in New York City.

It is critical to have a clear physical description of the ways in which COVID-19 is transmitted, so that individuals and institutions are able to visualize it and will understand how to protect themselves. Contrary to public health messaging, I, together with many other scientists, believe that a substantial share of COVID-19 cases are the result of transmission through aerosols. The evidence in favor