Air Changes Per Hour

01/10/2025

“How can we quantify how many times air is replaced in a room per hour?”

Air can get stuffy and polluted if it stays in a building for too long. People replace air over time to ensure it’s fresh on the inside. The number of times air is changed per hour is quantified by the Air Changes Per Hour. The air change per hour is quantified by taking the volume of air that is transferred from the outside per hour in a room and dividing it by the room volume. The U.S. CDC recommends an air change of at least 5 air changes per hour to reduce the number of viruses in a building.