Blue Pure 411 Auto Air Purifier; Filters the air in a 190 ft space in about 12.5 min (4.8x an hour, based on AHAM recommended removal rate) or up to 912 ft²in one hour on high speed to effectively lower particle levels and maintain a comfortable environment in large spaces like nurseries, guest rooms and home offices. An outer fabric washable pre-filter starts the process by removing larger particles. This also extends the life of the main filter. The main particle filter removes everything from pollen, dust and pet dander to viruses and bacteria. Then a layer of activated carbon goes to work, ridding households of light odors from pets, cooking and smoking. Only Blueair air purifiers use HEPASilent™ technology which provides maximum filtration with minimum noise. This dual filtration technology pioneered by Blueair combines electrostatic charging of particles and mechanical filtration using a unique filter design. Blueair air purifiers, therefore, produce more² clean air faster, cleaning your air quicker and much more quietly³ than traditional HEPA air purifiers.