Blueair's HEPASilent™ technology captures at least 99.97% of airborne particles down to 0.1 microns in size, removes germs and delivers especially high performance and efficiency by combining electrostatic and mechanical filtration technologies. This combination, pioneered by Blueair, delivers high Clean Air Delivery Rate (CADR) with whisper-silent operation and high energy efficiency. In fact, a Blueair air purifier works so quietly that you can not only sleep next to it, you might even have to check to make sure it is switched on. And on its lowest setting, a Blueair air purifier uses less electricity than a lightbulb.