Our Radiant Planet: Depletion of the Ozone Layer

Our Radiant Planet: Depletion of the Ozone Layer

Ozone is a relatively unstable form of molecular oxygen containing three oxygen atoms produced when upper-atmosphere oxygen molecules are split by ultra violet light. Stratospheric ozone is found in a broad band, extending generally from 15 to 35km above the earth. Although the ozone layer is surprisingly thin, it acts as a protective shield to the earth, as it filters out most of the harmful solar ultraviolet radiation (in particular UV-B) that would otherwise reach our planets surface.

Humans have damaged the ozone layer by adding molecules containing chlorine and/or bromine that lead to ozone destruction. The largest group among these are chloroflurocarbons (CFC's). At ground level, these molecules are very stable and have many uses in industrial and domestic applications, such as in spray cans, industrial solvents, degreasing compounds, and cooling in fridges. However when released into the stratosphere, such molecules can be broken down by energetic light rays (UV-C radiation) in a reaction that liberates an atom of chlorine, which destroys ozone by oxidising with the Ozone molecules, forming Cl-O and Oxygen. One atom of chlorine can destroy 10,000 ozone molecules! Atoms containing bromine, nitrous oxide, and hydrogen oxide radicals are also primarily dangerous. As a result, the Ozone in the stratosphere has been reduced to such an extent that ozone holes are appearing around the globe, in particular one over Antarctica that in 1995 measured 8.2 million square miles. This depletion has allowed more dangerous UV-B radiation to reach the earths surface.

So what effects will ozone depletion have on us? Although, at present, the ozone layer blocks out most of the damaging UVB radiation received from the Sun, a small amount slips by, damaging out skin in the form of sunburns and suntans. UVB radiation is strongly absorbed in the skin and in the outer layers of the eye....