The OZONE LAYER which lies in Stratosphere (16 to 48 kilometers above earth's surface) protects us from harmful UV radiation. Ozone layer help us by trapping harmful radiation from the sun. Ultraviolet(UV) rays are harmful rays which come from the sun. Ozone layer is made up of #O_3# or three atom of oxygen. When UV rays of 230 to 320 nm hit the ozone layer, #O_3# absorbs its energy and gets converted into #O_2# & then #O#.