UV radiations act on dioxygen to form ozone.There is dynamic equilibrium between the production and decomposition of ozone. The disturbance of this equilibrium results in ozone depletion.Chlorofluorocarbons mix with atmospheric gases and reach the stratosphere, where they are decomposed by UV rays to produce chlorine free radicals.These chlorine free radicals react with ozone to form oxygen and ClO⋅ free radicals which react with atomic O to produce more chlorine free radicals.This results in continuous breakdown of ozone present in the stratosphere damaging the ozone layer.