At the Airwasher's core are two cylindrical stacks of thin plastic disks, laid on their side and half-submerged in water. As a fan above sucks in dry, dusty air from the surrounding room, the stacks begin to rotate and pick up water. Some of the water is absorbed by the air (the stacks offer 5 square feet of disk surface), and some of it captures dust particles, causing them to drop into the tub. As a result, air leaving the unit is purified and humidified. The rotating disks are self-cleaning, and you can add oils to the water for a scent of pine, menthol, or tangerine.