School buildings need a fresh batch of air four to six times hourly to protect students and teachers against COVID-19, but typically only get about one-and-a-half air changes per hour, a public ...

“While we do not have the precise number of air changes per hour, LAWA mechanical engineers believe the HVAC systems provide on average of 10 air changes per hour,” Doten said. Public restrooms?

"And air change per hour to put numbers on it: Six air changes per hour is every 10 minutes the full volume is refreshed, the full volume of the space.

On the flip side, "At its lowest setting, it only cleans 1,920 cubic feet per hour, meaning that same living room gets just about 1 air change per hour." ...

But in most indoor settings, the air change falls below the Harvard standard for healthy air. "For example, in your home, typically you get half an air change per hour.

The East Coast and Midwest getting hit by wildfire smoke show that air pollution affects everyone and we need better protections, especially to confront climate change.

“If the ceiling height in the classroom is 10 feet, that’s three total outside air changes per hour,” says Miller, who is also an indoor air quality expert.

In May, the Centers for Disease Control and Prevention recommended five so-called air changes per hour — the equivalent of replacing all the air in a room — in all buildings, including schools.

As Chris Michael, founder of Meaco, warns: “If it's too small, it won't clean the air properly, no matter how good the filter is. You need enough air changes per hour for the space it’s in.” ...

The agency had advised people to ventilate indoor air before, but this is the first time a federal agency has set a target – five air changes per hour – for how much rooms and buildings should ...