SurroundAirTM vent system delivers exceptional air exchange (up to 500 cubic feet per minute) without annoying drafts, performance that earned the 501 Best of Class ranking in independent AHAM testing of Clean Air Delivery Rate.

Easy maintenance: simply open the unit's lid, lift out and drop in filters every 6 months. Choose the optional SmokeStop Filter Kit for better protection from smoke and other airborne gases

Amazon.com Review
For rooms up to 620 square feet, this air purification system features two-stage HEPASilent technology that captures 99.97-percent of 0.1 micron particles, including allergy-provoking pollen grains, dust mites, mold spores, and pet dander particles. Particles that a HEPA filter alone might miss are captured with an electrostatic charge. HEPASilent technology moves particles through an enclosed ion chamber, which attaches a charge to the particle itself. Charged particles cling more easily to the filter media, resulting in higher filter efficiency overall. Because most electrostatic air cleaners charge the filter media itself, the charge dissipates over time and renders the filter less efficient. By constantly charging incoming particles, instead of the filter, HEPASilent technology keeps on working effectively.

The air purifier's HEPASilent filter technology is geared towards a more environmentally friendly design as well. Its nontoxic polypropylene filter contains millions of ultra-thin fibers that trap tiny particles as they pass through the pleats. One of the least harmful plastics for human health and the environment, polypropylene works without outgassing or shedding irritating microscopic fibers into the air. Because polypropylene is waterproof, the filter resists contamination from bacteria, viruses, and mold naturally, without chemical additives. And as used filters are discarded and decompose, the filter media converts into harmless carbon dioxide and water.

Not only does the unit clean air with environmentally friendly filters, it's HEPASilent filter technology also allows for extremely quiet operation. On the lowest setting, the unit emits no more sound than a desktop computer. With its HEPASilent filter technology, particles are trapped with both mechanical and electrostatic filters so that in combination, the two filters create a filter system through which air flows freely and the fan doesn't have to work so hard. The unit's design is also geared towards quiet operation with its noise-muffling steel housing. Not only quiet, but the air purifier is energy efficient as well, costing about the same amount to clean indoor air as it does to power a light bulb--15 watts on low to 95 watts on high.

The air purification system operates quietly, efficiently, as well as inoffensively. Instead of discharging a windy stream of filtered air, the unit diffuses air gently through an area six times greater than the average air cleaner. Its SurroundAir system achieves peak performance without annoying drafts by drawing in dirty air from the sides and bottom, moving it through a less dense filter media, and releasing clean, filtered air from the sides and top. Operating on its lowest setting, the system produces virtually no noticeable draft, while still providing an exceptional air exchange rate.

The air purifier features a sleek, contemporary, Swedish design and is easy to use and maintain. Simply plug it in, select the speed setting, and it is ready to go, with a bright blue power "on" light to show that it's working. The grilles and powder-coated steel exterior are easy to wipe clean, and when the filter needs to be replaced (twice yearly), just open the lid, lift out the old filters, and drop the new ones in. Choose the optional SmokeStop filter kit for better protection from smoke and other airborne gases. This quiet, efficient, easy-to-use air purifier measures 26 by 20 by 13 inches and carries a 10-year warranty. --Catie Unger