Seven Stages of Purification:The 7-Stages: Ultraviolet (UV) SterilizationEach air purifier by Rocky Mountain Air® features ultraviolet sterilization to make your home or office safer by sanitizing the air you breathe. Our air cleaners contain dual UV lamps to, with each purification cycle, kill microorganisms, such as viruses, bacteria, mold, and mildew. Ultraviolet Germicidal irradiation (UVGI) is an important addition to any HEPA air filter, as UV lamps are known to kill 99.9% of microorganisms they come in contact with. The combination of UV sterilization, HEPA filtration, and our other four purification stages make Rocky Mountain Air® purifiers an essential means of keeping the air in your home safe and clean.