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(a) What are the after effects of the degradation of ozone ?

(b) How does it affect human health ?                                      (2 marks)


(a) Ozone depletion causes holes in the stratosphere which allows UV rays to enter the earth.

     Ozone layer protects us from ultraviolet radiations. UV rays are extremely harmful for living

     organisms since DNA and proteins of living organisms absorb UV rays and its high energy 

     breaks the chemical bonds within these molecules.


(b) UV-B damages DNA and mutation may occur. It causes ageing of skin, damages the skin cells,

     may cause skin cancer. In human eye, cornea absorbs UV-B radiation and a high dose of UV-B

     causes inflammation of cornea called snow-blindness, cataract, etc. Such exposure may

     permanently damage the cornea.