The Ozone layer present in the Stratosphere of the atmosphere forms a thick layer (16 - 40 km) and protects the life on earth against the ultraviolet radiations coming from the sun.
The Chlorofluorocarbons (CFC’s) that are widely used in coolants, air conditioners, refrigerators escape into the earth’s atmosphere as aerosols.
They dissociate to form Chlorine which acts on Ozone and reduces it.
The Chlorine and Chlorine free radicals are responsible for ozone hole over Antarctica.
Cl + O3 -----------> ClO + O2
CFCl2, CF2Cl2 -----------> ClO + O2