Dramatic loss of ozone in the lower stratosphere over Antarctica was first noticed in the 1970s by a research group from the British Antarctic Survey (BAS)
Over Antarctica (and recently over the Arctic), stratospheric ozone has been depleted over the last 15 years at certain times of the year.
The British Antarctic Survey's first documentation of the Antarctic ozone hole
The Dobson Unit (DU) is the unit of measure for total ozone.
The ozone is created when ultraviolet radiation (sunlight) strikes the stratosphere, dissociating (or "splitting") oxygen molecules (O2) to atomic oxygen (O).
The atomic oxygen quickly combines with further oxygen molecules to form ozone:
Ozone is also destroyed by the following reaction: O + O3 ->O2 + O2
NSF-funded study of the phenomenon alerted the world to the danger of chlorofluorocarbons, or CFCs.