CFCs find wide use as refrigerants. CFCs discharged in the lower part of
atmosphere move upward and reach stratosphere. In stratosphere, UV rays
act on them releasing Cl atoms. Cl degrades ozone releasing molecular
oxygen, with these atoms acting merely as catalysts, Cl atoms are not
consumed in the reaction. Hence, whatever CFCs are added to the
stratosphere, they have permanent and continuing effects on ozone
levels.