# Depletion of Ozone Layer

The ozone layer in stratosphere absorbs the harmful ultraviolet rays coming from the sun. This layer does not allow the uv rays to reach the earth surface. So, it acts as a protective layer for the earth. It has been found that the layer of ozone layer is thinning due to the excessive use of green house gases like carbon monoxide, nitric acid, Chloro Fluoro Carbon etc. This is called ozone layer depletion. Chloro Fluoro Carbon is major responsible factor for the depletion of ozone layer.

How does Chloro Fluro Carbon deplets ozone layer?

CFC absorbs uv rays from the sun and gets decomposed to give chlorine atom. The chlorine atom decomposes ozone. The chlorine atom is regenerated from ClO and combines with another ozone molecule. The oxygen atom generated at the decomposition of ClO combines with ozone to decompose it into oxygen molecule. Thousands of ozone molecules are being destroyed through this chain reaction. This creates a depletion of ozone layer. In this way ozone layer is depleted by CFC. The reaction involved is shown below:
$$\ce{CHClF2->[hv]CHF2 + Cl}$$
$$\ce{Cl + O3->ClO + O2}$$
$$\ce{ClO->Cl + O}$$
$$\ce{O + O3->2O2}$$

Note: Researchers have estimated that a single molecule of CFC can destroy one lakhs of ozone molecules.

Effect of ozone layer depletion:

– It causes hole in ozone layer which is called ozone hole.
– The harmful UV rays can reach the earth surface directly and causes skin cancer, blood cancer etc.
– It causes reduction in crops productivity.
– It can cause rise in temperature of the earth surface consequently leading to global warming.
– It can cause many life threatening diseases and the existence of living beings will be in vain.

So, researcher has urged all the people to reduce the use of harmful green house gases and focus on the alternative source of energy. Awareness campaign should be launched in order to aware all the living people in the earth.

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