Blueair is the system for people living with allergies asthma or other respiratory conditions or for anyone who wants cleaner more breathable air. The 402 effectively purifies air in rooms as large as 365 square feet. Using patented two-stage HEPASilent technology it captures 99.97% of the tiniest 0.1 micron particles on level one including allergy-provoking pollen grains dust mites mold spores and pet dander particles. This same filter technology earned the larger Blueair units Best of Class ranking in independent testing of Clean Air Delivery Rates. The 402 provides comparable performance for mid-sized rooms. Value-added features include quiet operation low energy use galvanized steel construction and easy maintenance: simply open the side slide out used filters and drop in replacements every 6 months.