(N/A) Chlorofluorocarbons (CFCs),used as refrigerants and aerosol propellants,are released into the atmosphere.
In the stratosphere,they decompose in the presence of ultraviolet $(UV)$ radiation to release chlorine atoms (free radicals):
$CF_{2}Cl_{2} \xrightarrow{hv} ^{\bullet}CF_{2}Cl + Cl^{\bullet}$
These reactive chlorine atoms then react with ozone to deplete the ozone layer through the following chain reactions:
$Cl^{\bullet} + O_{3} \rightarrow ClO^{\bullet} + O_{2}$
$ClO^{\bullet} + O \rightarrow Cl^{\bullet} + O_{2}$
It is observed that a single molecule of $CFC$ can destroy up to $1000$ molecules of ozone.