If you’re not moving the air, you’re not cleaning the air. Experts recommend at least 4 air changes per hour for optimal removal of airborne particles from the air. You can rest assured that AmazingAir purifiers are powerful enough to clean the air 4 times per hour, or every 15 minutes, for their respective room size coverage to deliver you pure, protected air. Many air purifiers base their room size coverage on only 1-2 air changes per hour (ACH). It is important to check that an air purifier has a high enough CADR to circulate the air in the room at least four times per hour.