As the nation reopens after COVID-19 restrictions, people across the country are making decisions about going back to the office or putting their children back in classrooms. But how can you make the right call? We asked the experts how to improve indoor air quality, and what questions to ask your boss or school administrator. “Often indoors, people are the source of contaminants,” says Dr. Shelly Miller, a professor of mechanical engineering at the University of Colorado Boulder.

Your chances of being infected depend on the size of the room and the number of people infected with COVID-19 inside.

“When they talk, talk loudly, when they breathe, small respiratory aerosols are released,” Miller said. If you’re in a classroom, office or other enclosed space, these aerosols can build up over time. “It’s like if you’re in a smoky bar,” Miller says. “When it opens, there’s not a lot of smoke, but the more people smoke, it becomes a cloudy room. You can think of virus being released like that.”

Read article