QuietClean Tower Air Purifier captures up to 99 percent of ultra-fine particles such as smoke, dust, pollen, mold spores, pet hair and dander from air passing through the filter. It also helps reduce odors and VOCs. Air purifier includes a permanent, washable ifD filter and an installed, washable pre-filter for easy maintenance. Filter check/reset light reminds you when it's time to change your filter. Filters should be cleaned every 3 months for optimal filtration. Features include three cleaning levels and optional oscillation. Quiet operation enables use while you sleep, watch TV or work. Tower design circulates air in a 170 square foot room up to 4.8 times per hour. Electronic, push-button controls and dimmer feature simplify the operation. Air purifier is AHAM verified and is independently tested for efficiency in reducing smoke, dust and pollen. Reach-through handle allows easy portability from room to room.