Patented HEPASilent™ technology is more efficient than other air purifiers using traditional HEPA filtration, trapping up to six times more dirt, dust, allergens, pollen, smoke, mold spores, bacteria, and viruses to keep indoor air fresh, clean and healthy. Blueair 600 Series purifiers feature very high Clean Air Delivery Rates (CADR) in independent testing results by AHAM, a tribute to the efficacy of this filter. Change filter every 6 months for optimal performance.