The PureStar 1000 is a true HEPA air purifier with the ability to filter an average size room (10X10) with 7 air changes per hour. This means that the entire room can get a breath of fresh air approximately every 10 minutes. In addition the PureStar 1000 can change the air in a 500 square foot area 36 times a day! True HEPA filtration is recommended by doctors and is used by hospitals, research labs, and computer clean rooms.