UV radiation (aka ultraviolet radiation) is a form of radiation, usually emitted by stars.
Protection from UV radiation comes from atmospheric protection, in terms of an ozone layer. Planet such as Avnil are greatly effected from UV radiation due to minimal atmospheric protection, this creates hazardous conditions for outdoor travelling and minimal life. Two Ancient force field devices can create a force field that blocks UV radiation much like an ozone layer. (SG1: "The First Commandment")