Air purifiers are special devices developed to remove contaminating particles contained in the air we breathe. There are a lot of different types of such gadgets, and they differ in the working principle. Filter-based devices are used everywhere. Usually, such gadgets are a part of the HVAC system. They filter out dust from the air very effectively, but their main drawback is that they hinder the flow of air. Another type is ionizing devices. They operate by creating different charges on dust particles, causing them to pull themselves to each other and fall down. Ozone generating devices have a somewhat similar way of functioning. They create oxygen-rich particles that can disinfect the air. Finally, another type of air cleaning products is an ultraviolet lamp, which eliminates bacteria.