I have friends and relatives that have installed UV lights on their furnace. What are they for?

I have friends and relatives that have installed UV lights on their furnace. What are they for?

UV is the abbreviation for ultraviolet. Located in the return air ductwork and by the indoor cooling coil, the ultraviolet air treatment system continuously emits high – intensity ultraviolet (UV) energy. The energy eliminates (kills) a very high percentage of airborne bacteria and germs passing over the UV light field inside the ductwork. The UV light mounted next to the indoor cooling coil will help eliminate the growth of mold, mildew and other contaminates from the drain pan and coil surface. At Air Specialisti we recommend installing non-ozone-producing UV products.