TOMS provides dramatic visual evidence of the annual growth and decay of the Antarctic ozone hole. The ozone losses over Antarctica result from reactions with the products of man-made chlorine and bromine compounds. Because of the tilt of the Earth's axis, continuous darkness falls at the South Pole from March 21 to September 21. The dark region in the middle of the July 1 total ozone picture is polar night, where TOMS cannot make measurements. Ozone losses are in blue. Beginning in August, returning sunlight reaches the edges of Antarctica providing chlorine and bromine compounds with energy to rapidly destroy ozone. By mid September, the ozone loss peaks, creating an ozone hole over Antarctic.
or more information see http://www.gsfc.nasa.gov/topstory/2003/1208toms.html
