Ozone-oxygen cycle
When Ozone in the Earth's upper atmosphere is hit with solar radiation, it undergoes a chemical reaction:O3 + radiation ---> O2 + O.
Within a fraction of a second, another reaction occurs.
O2 + O ----> O3 + heat.
These reactions lessen the severity of solar radiation on the Earth's surface.
Unfortunately, CFCs (Chlorofluorocarbons) tend to react with O3 molecules, stripping of the extra oxygen molecule and leaving O2.