For months, experts have offered all sorts of warnings about how the coronavirus is transmitted via droplets—large respiratory droplets, produced via coughing, sneezing, or talking, that can land in nearby people's mouths and noses, be inhaled in their respiratory tracts, or get on their hands after landing on surfaces. But scientists are increasingly warning that the virus that causes COVID-19 is likely also airborne, meaning it can also be transmitted via aerosols, smaller particles that linger in the air longer, rather than quickly dropping to the ground as droplets do. "Evidence suggests that [the novel coronavirus] is silently spreading in aerosols exhaled by highly contagious infected individuals with no symptoms," three experts write in a commentary in the journal Science cited by CNN. And a fourth expert warns in the Washington Post that "we cannot keep ignoring the possibility of airborne transmission."
And all of this comes after the CDC issued new guidance saying the virus is primarily spread from person to person, and that it "does not spread easily" via surfaces, though Fox News notes that guidance was later walked back. A growing amount of evidence suggests aerosols "can accumulate, remain infectious in indoor air for hours, and be easily inhaled deeply into the lungs," one of the three experts who published in Science tells WebMD. She says people should think about how far away they can smell a BBQ or cigarette smoke—"That’s how far aerosols can travel between you and another person," per WebMD. What does this all mean? All four experts agree: Masks are crucial. And six feet of distance may not be enough in an indoor setting; at the Post, Joseph Allen explains how ventilation, filters, and other healthy building strategies can also help slow the spread indoors. (Read more coronavirus stories.)