Natural Resources — Science STD 9 — Question

The ozone layer is a deep layer in the stratosphere, encircling the Earth, which has large amounts of ozone in it. This layer shields the entire Earth from much of the harmful ultraviolet radiation that comes from the sun. Ozone is a special form of oxygen, made up of three oxygen atoms rather than the usual two oxygen atoms.

It is formed when some type of radiation or electrical discharge separates the two atoms in an oxygen molecule (O₂), which can then individually recombine with other oxygen molecules to form ozone (O₃).

Reduction in the concentration of ozone layer is called ozone depletion. Ozone depletion is caused by certain chemicals called ozone depleting substances. They include chlorofluoro carbons, methyl bromide, nitrogen oxides and chlorine.

Effects of ozone depletion: Depleting ozone layer allows more ultraviolet (UV) radiations to pass through it, which reach the earth's surface. These UV rays cause various harmful effects on human beings, animals, plants and environment such as:

1. Skin cancer.
2. Damage of eyes.
3. Damage of immune system.
4. Decreased crop yields.