Fellowes AeraMax Air Purifier features a 4-stage hospital-type filtration that effectively cleans air in small spaces 200-400 square feet. The Smart Sensor detects air quality and automatically adjusts the fan speed to keep your air purified. A True HEPA filter with antimicrobial treatment safely removes 99.97 percent of airborne particles as small as 0.3 microns, including allergens, viruses, and cigarette smoke. Proven effective at capturing the airborne flu virus. Carbon filter removes odors. The air purifier also includes the Aera+ Mode for allergy and cold/flu seasons and features ultra-quiet operation.