Polar regions experience the greatest changes in ozone concentrations, with severe ozone depletion occurring each springtime, particularly over Antarctica. This is due significantly to the special meteorological conditions which exist in these regions of the world.
The topography and circular shape of Antarctica is such that a stagnant whirlpool of extremely cold stratospheric air forms over the region during the long polar night. The air circulates within this polar vortex all winter, becoming cold enough to allow the formation of polar stratospheric clouds which accelerate and enhance stratospheric ozone destruction when sunlight returns during early spring. Such a vortex also exists in the Arctic region, but to a lesser degree. The Arctic region consists of many distinct landmasses and islands spread out around the North Pole, and so the air cannot circulate quite as easily.