In order to understandabout ozone depletion, we must first know what is meant by an ozone layer, whatis an ozone molecule and also what is the ultimate function of the ozone layer.
Ozone layer is a layer located between 20 and 25 kilometres above the surfaceof Earth, in a region called stratosphere. Most of the ozone is located in thisregion while 10% of the ozone is located in a region called troposphere, whichis around 12 kilometres above the Earth’s surface. The ozone found in thesedifferent layers have the same chemical structures. Ozone is a molecule thatconsists of three oxygen atoms.
It is highly unstable and will react readilywith other atoms or molecules to produce a stable compound. An ozone molecule hasthe duty to absorb the ultraviolet light (UV light) which is emitted by theSun. Indirectly, the ozone molecules act as a protection layer which will avoidthe penetration of this radiation to the surface of the Earth.
This UVradiation, specifically UV-B and UV-C, is of very high frequency and is capableenough to cause severe biological damages in living organisms. Some scientistsalso claim that it is because of the stratosphere layer that there is life onthis planet because without this layer, survival may be impossible. In the tropospherelayer, ozone molecules are found in a very small concentration.
However, thissmall amount is still enough to cause biological harm and changes. Ozonedepletion on the other hand, is the thinning of the ozone layer. It was duringthe 1970s that scientists realised that the ozone layer was depleting. Aftersome observations and experiments, the scientists concluded that the cause ofthis depletion is chlorofluorocarbon (CFC) and few other chemicals used inaerosols, refrigeration and cleaning agents. Scientists back then also learntthe harmful effects this depletion can result on living organisms as well asthe environment. In 1985, it was found that the stratospheric region above Antarcticahad declined by around 40% since 1977. There was an evidence of a large ‘ozonehole’ above this continent.
To add to the danger, even the sky above the Arcticregion has these holes. Peopleback then feared that this phenomena may bring drastic changes to human life.As a result, the Montreal Protocol on Substances that Deplete the Ozone Layerwas introduced in 1987. This protocol banned the production of CFC and otherozone depleting substances. As a result of this act, there were improvements inthe ozone layer in 1989.
Ozone layer then began to stabilize and till date, isstill recovering. However,there are many people who are not seem to be bothered about the harmfulsubstances they’re using which will contribute to the thinning of the ozonelayer. It has been reported that with every one percent depletion of the ozonelayer, there is two percent increase in the concentration of UV-B, the mostharmful ultraviolet radiation.
In the following sections, we will discuss onhow ozone depletion occurs, the effects of this phenomenon and also ways toprevent further depletion of this layer.