What is ozone shield? How is it being corroded?

Ozone shield or ozone layer is a layer that protects earth from the harmful ultraviolet radiations coming from the sun therby protecting us from serious ailments and thus acting as a shield. Ozone molecules form when a single O atm reacts with oxygen O2 molecule.

Chlorine containing compounds are major reason for the corrosion of ozone layer. Chlorofluorocarbons and certain other ozone depleting substances that contain chlorine and/or bromine are responsible for depletion of ozone layer. CFCs are made of chlorine. One single atom of chlorine destroys 1000 molecules of ozone.