Why does ozone hole form over Antarctica ? How will enhanced ultraviolet radiation affect us ? 

Explanation

A large amount of ODS (Ozone Depleting Substances) like `CFCs, N_(2)O`, halons, `SO_(2), CH_(4), Cl-` are released by advanced countries like USA, Japan, European countries. These are released in stratosphere, drift towards poles and reach there before the coming of winter. During winter (temp. `85^(@)C`) ice clouds are formed over Antarctica and no sunrise is received in polar areas. It catalyses release of Cl from CFCs. With the coming of spring season, Cl reacts with ozone in the presence of sunlight and converts `O_(3)` into `O_(2)` causing ozone depletion/thinning of ozone shield in stratosphere called ozone hole. This hole disappears in summer due to free mixing of air of Antarctica with thereshold of the global air. Effect of Enhanced UV Radiation, (i) Snow blindness or inflammation of cornea (ii) Damage of skin cells and development of skin cancer, (iii) Damage to nucleic acids and proteins, (iv) Reduced immunity (v) Higher number of cataracts in humans.