Before we move on with the story let’s understand the ozone layer first. As you have studied in school, Ozone is a gas. Its chemical formula is O3. While the chemical formula of Oxygen is O2. The ozone molecule is made up of 3 oxygen atoms. About 600 million years ago the ozone layer was formed around Earth. This is a zone in the atmosphere of Earth which is about 15-35 km above the surface of Earth. 90% of the ozone on Earth is found in this area.
Ozone concentration is found to be highest at 32km above the surface which is at 0.0015%. It’s not a big number. This gas is found in a very small amount in the atmosphere. But even such a small amount is important for the Earth. Ozone is made from oxygen when the sun’s ultraviolet radiation hits the oxygen molecules. A very simple chemical reaction takes place. Because of ultraviolet radiation, the oxygen molecules split into oxygen atoms. And when these separated atoms mix with the oxygen molecules, ozone is formed.
O2 + O = O3
