ultraviolet light is a type of ionizing radiation. it can damage or kill cells. any electromagnetic radiation (light) that has a wavelength shorter than 450 nm may cause trouble. therefore, humans that live in places with more ultraviolet light have adapted by getting darker skins. pigments absorb the ultraviolet radiation, so it does not get through the skin to kill or injure cells inside. injury to the skin by ultraviolet is called "sunburn."