Ozone is mainly found in two regions of the Earth's atmosphere. Most (90%) are found in stratosphere and some (10%) are found in troposphere.
The ozone layer protects the DNA of all surface dwelling life, by absorbing UltraViolet-B from our Sun.
It is caused by the release of chlorofluorocarbons (CFCs), hydrofluorocarbons (HCFCs), and other ozone-depleting substances (ODS), which were used widely as refrigerants, insulating foams, and solvents.