Question

Why ozone hole forms over Antarctica? How will enhanced ultraviolet Radiations affect us?

Answer 1

The ozone hole is more prominent over the region of Antarctica. It is formed due to an increased concentration of chlorine in the atmosphere.

Chlorine is mainly released from chlorofluorocarbons (CFC’s) widely used as refrigerants. The CFC’s magnate from the troposphere to the stratosphere, where they release chlorine atoms by the action of UV rays on them. The release of Chlorine atoms causes the conversion of ozone into molecular oxygen. One atom of chlorine can destroy around 10,000 molecules of ozone and causes ozone depletion.

The formation of the ozone hole will result in an increased concentration of UV - B radiations on the Earth’s surface. UV −B damages DNA and activates the process of skin ageing. It also causes skin darkening and skin cancer. High levels of UV −B cause corneal cataract in human beings.

Answer 2

A large amount of ODS (Ozone Depleting Sub-stances) like CFCs, N₂O, halons, SO₂, CH₄, 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 03 into 02 causing ozone depletion/thining of ozone shield in stratosphere called ozone hole. This hole disappears in summer due to free mixing of air ofAntarctica with therestofthe 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.