Permanent HEPA filter captures 99.97% of microscopic allergens such as mold spores, pollen, dust, smoke and pet dander as small as 0.3 microns. Eliminates airborne bacteria and viruses. Circulates room air up to 5 times an hour. Patented HEPA SurroundSeal™ ensures no air leaks around the filter to maximize efficiency. Carbon pre-filter helps reduce odors. Push-button controls, three air-cleaning levels. Low maintenance: Simply vacuum HEPA filter twice a year.