Ozone layer is a belt of naturally occurring gas Ozone. It is 15 to 30 kilometers above the earth and acts as a shield from entering harmful ultraviolet B radiations from the sun to earth.
Ozone layer is deteriorating due to release of pollution containing chemicals like chlorine and bromine. Chlorofluorocarbons and chemicals found in spray aerosols are primary culprits for ozone layer depletion.
Depletion of ozone layer allows large amounts of UVB rays to reach earth which can cause skin cancers and cataract in humans, harms flora fauna as well.