UV air purifiers use ultraviolet light to kill bacteria and pathogens in your air, usually working in tandem with a traditional filtration system. While highly effective, this type of air purifier comes with some added risks you should be aware of before buying. First, the high-energy UV light can damage the skin if you become exposed to it. While the UV light is normally concentrated within the device, contact can occur when changing filters, cleaning, or other maintenance. Because of the high energy, it presents more of a risk than other forms of UV light. Second, ozone is created as a byproduct of the filtration system in UV filters. In small quantities, ozone doesn't damage your body. However, it can eventually cause coughing and shortness of breath and exacerbate asthma. This is especially bad for devices that are supposed to clean your home’s air.