Blueair 501 Console Air Purifier Patented two-stage HEPASilent technology captures 99.7% of the tiniest. 1 micron particles, including allergy provoking pollen grains, dust mites, mold spores and pet dander particles Six air exchanges per hout Efficient SurroundAir vent system exchanges up to 500 cubic feet per minute without annoying drafts No ozone emission Earned Best of Class ranking in independent AHAM testing of Clean Air Delivery Rate