“The ozone layer” refers to the ozone within stratosphere, where over 90% of the earth’s ozone resides. Ozone is an irritating, corrosive, colorless gas with a smell something like burning electrical wiring. Ozone is a tri-atomic form of oxygen, i.e., each molecule of ozone has three oxygen atoms and is produced when oxygen molecules (O2) are broken up by energetic electrons or high energy radiation. Ozone in the stratosphere protects life on Earth as it limits penetration of ultraviolet radiation through the atmosphere, but it is considered a pollutant in the troposphere (close to the ground). The amount of ozone in the atmosphere is measured in Dobson units (DU). One DU is about twenty-seven million molecules per square centimeter. The average thickness of the atmospheric ozone layer at any place varies from month to month, but is generally between 260 and 330 DU.

Ozone is a special form of oxygen with the chemical formula O3. The oxygen we breathe and that is so vital to life on earth is O2.Ozone constitutes a very small part of our atmosphere, but its presence is nevertheless vital to human well-being. Most ozone resides high up in the atmosphere, between 10 and 40km above Earth’s surface. This region is called the stratosphere and it contains about 90% of all the ozone in the atmosphere. Ozone in the stratosphere absorbs some of the Sun’s biologically harmful ultraviolet radiation. Because of this beneficial role, stratospheric ozone is considered “good” ozone. In contrast, excess ozone at Earth’s surface that is formed from pollutants is considered “bad” ozone because it can be harmful to humans, plants, and animals. The ozone that occurs naturally near the surface and in the lower atmosphere is also beneficial because ozone helps remove pollutants from the atmosphere.

Causes of Ozone Layer Depletion

The ozone layer depletion is a major concern and is associated with a number of factors. The main causes responsible for the depletion of the ozone layer are listed below:

Chlorofluorocarbons:

Chlorofluorocarbons or the CFC are the main cause of ozone layer depletion. These are released by soaps, solvents, spray aerosols, refrigerators, air-conditioners; etc. The molecules of chlorofluorocarbons in the stratosphere are broken down by the ultraviolet radiations and release chlorine atoms. These atoms react with ozone and destroy it.

Unregulated Rocket Launches:

Researchers say that the unregulated launching of rockets result in much more depletion of ozone layer than the CFCs does. If not controlled, this might result in a huge loss of the ozone layer by the year 2050.

Nitrogenous Compounds:

The nitrogenous compounds such as NO2, NO, N2O are highly responsible for the depletion of the ozone layer.

Reducing of ozone

Limiting the emission of certain common pollutants reduces the production of excess ozone in the air surrounding humans, plants, and animals. Natural emissions from the biosphere, mainly from trees, also participate in reactions that produce ozone. Major sources of pollutants include large cities where fossil fuel consumption and industrial activities are greatest. Many programs around the globe have already been successful in reducing or limiting the emission of pollutants that cause production of excess ozone near Earth’s surface.

We can protect ozone layer depletion by avoiding excessive use of pesticides, air pollutants, chemicals used for agriculture, toxic gas released by motor vehicles and CFC’s.