Ozone hole forms over Antarctica where no one lives and no pollution is present but not over Newyork, Bangalore etc., (polluted cities). It is because CFCs and ozone-depleting substances (ODS) released worldwide accumulates in the stratosphere and drifts towards, Antarctica in winters (July – August) when temperatures is -’85°C in Antarctica.

In winters polar ice clouds are formed over Antarctica. It provides a catalytic surface for (CFCs and other ODS to release CL and other free radicals that breakdown ozone layer forming an ozone hole during spring in presence of sunlight. In summer, the ozone hole disappears due to mixing of air worldwide.

Ozone holes allow UV radiations (UV_A & UV_B) to reach earth’s surface. Which was earlier reflected by the ozone layer. UV_B damages DNA, skin cells and causes mutations and skin cancers respectively. UV_B even causes corneal damage (Snow Blindness).