For much of 2020, doctors and public-health officials thought the virus was transmitted through droplets emitted from one person’s mouth and touched or inhaled by another person nearby. We were advised to stay at least 6 feet away from each other to avoid the droplets that would most likely fall to the ground within seconds. Since the droplets might contaminate surfaces, we washed our produce, sanitized our hands (to the tune of “Happy Birthday”), cleaned doorknobs and railings with alcohol, and opened our Amazon deliveries outdoors because the boxes might be contaminated.
A small cadre of aerosol scientists had a different theory. They suspected that Covid-19 was transmitted not so much by droplets but by smaller infectious aerosol particles that could travel on air currents way farther than 6 feet and linger in the air for hours.
“My first and biggest wish is that we had known early that Covid-19 was airborne,” says [emergency room physician Megan Ranney].
John Volckens, professor of environmental health and an aerosol scientist at Colorado State University in Fort Collins, Colo., says, “Once you’ve realized that, it informs an entirely different strategy for protection.” Masking, ventilation and air cleaning become key, as well as avoiding high-risk encounters with strangers, he says.
