Ozone layer of upper atmosphere is being destroyed by 

CFCs are used as refrigerants in refrigerators and AC. CFCs discharged in the lower part of atmosphere move upward and reach the stratosphere. In the stratosphere, UV rays act on them releasing Cl atoms. Cl reduces the ozone and releases molecular oxygen, 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. This has resulted in the formation of a large area of thinned ozone layer, commonly called as the ozone hole.