A best seller, the Blueair 403 air purifier gets you the most bang for your buck by maximizing clean air delivery in mid-size rooms up to 365 square feet. Independently tested by the Association of Home Appliance Manufacturers (AHAM) for Clean Air Delivery Rate (CADR), the Blueair 403 has a rating of 240 cubic feet per minute for smoke, dust, and pollen with a superior 5 air changes an hour. Blueair 403 is whisper-silent on low and delivers designed white noise on higher speeds by using a double-suction radial fan to balance sound frequency making it more pleasing to the ear. Blueair’s patented HEPASilent® technology uses both electrostatic and mechanical filtration to trap 99.97% of particles from the air down to 0.1 microns in size. The technology works by charging harmful particles as they pass through the encapsulated ion particle-charging chamber of the air purifier, successfully locking in particles large and small into the unique filter design. The Blueair 403 air purifier comes with a timer to alert you when your filter needs changing. The timer can be attached to the unit, refrigerator, or anywhere else. Simply open the door on the front of your Blueair 403 unit to change the filter. Weighing in at 33 lbs, the Blueair 403 features a handle, so you can move your air purifier around your home or office with ease.