Researchers say strong ventilation indoors should accompany other measures to prevent the spread of the virus. Driving the thinking is mounting evidence that the new coronavirus is transmitted through the air among people with prolonged exposure to the pathogen, even when close contact is avoided.
Health scientists and mechanical engineers have started issuing recommendations to schools and businesses that wish to reopen for how often indoor air needs to be replaced, as well as guidelines for the fans, filters and other equipment needed to meet the goals.
Some businesses have begun taking such steps, but in aging schools nationwide, strengthening ventilation may be difficult.
— The Wall Street Journal