(The Conversation is an independent and nonprofit source of news, analysis and commentary from academic experts.)

Byron Erath, Clarkson University; Andrea Ferro, Clarkson University, and Goodarz Ahmadi, Clarkson University

(THE CONVERSATION) When someone coughs, talks or even breathes, they send tiny respiratory droplets into the surrounding air. The smallest of these droplets can float for hours, and there is strong evidence that they can carry live coronavirus if the person is infected.

Until this week, however, the risk from these aerosols wasn't incorporated into the World Health Organizat...