The Sharp Plasmacluster Ion Air Purifier with True HEPA Filtration and Humidification offers a unique combination of air treatment technologies and a one-touch automatic air quality control system to make you and your family more comfortable all year round. The automatic air quality control system uses sensors to constantly monitor the air quality in your room, adjusting for air purity and optimum humidity level, and will also indicate when filters should be cleaned. The KC-850U helps remove pollutants and common allergens such as pollen, dust, pet dander, and smoke with an ultra quiet fan that draws air through a three-stage filter system including a permanent micro-mesh pre-filter, washable activated carbon filter, and a long-life True HEPA filter, which captures 99.97% of particles as small as 0.3 microns from the air that passes through it. The KC-850U also reduces germs, bacteria, viruses, odors, mold, and fungus by using patented Plasmacluster Ion Technology, which disperses positively and negatively charged ions throughout the room to safely break down microorganisms and odors (even those trapped in fabric, carpeting, and drapery!). It is an ideal solution for allergy sufferers, asthmatics, pet owners, and smokers, and when used in humidify mode, can help relieve congestion, cough, and dry and swollen nasal passages. It is best used in a bedroom, living room, study, or exercise room. In addition to auto mode, there are 3 manual fan speeds. The unit has LibraryQuiet™ operation (as quiet as 17 decibels, or the sound of rustling leaves) and is ENERGY STAR® rated, so you can run the unit continuously while saving money and energy.