Environmental Issues — BIOLOGY STD 12 Science — Question

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.

1. When released in stratosphere, these substances drift towards poles and get accumulated on the ice clouds formed at high altitudes.
2. Ice provides a surface on which breakdown of all the CFC compounds takes place to release chlorine atom.
3. These chlorine atoms breakdown ozone resulting in thinning of the ozone layer. Normally, the ozone layer plays a protective role by absorbing harmful UV radiations but reduction in its thickness allows UV rays to reach Earth's surface.

Effects of ultraviolet radiation on humans:

1. Early ageing of skin.
2. Increased incidences of cancer of the skin.
3. Cataract of the eyes.
4. Inflammation of cornea of the eye (known as snow blindness).
5. Weakened immune system.