The Ozone Cycle

In this picture we are seeing how the ozone layer is destroyed and the effects of that destruction. Certain compounds such as chlorofluorocarbons, CFC’s, are released into the atmosphere by human activities and these CFC’s particularly, they are very, very unreactive at the atmospherical ground level and they go all the way up to the stratosphere and then the CFC’s dissociate or give up the chlorine. Each chlorine atom is capable of destroying or basically turning ozone into oxygen and which again doesn’t have the same capability as ozone does in shielding us from the UV radiation. And once that ozone layer or the number of ozone molecules in that layer goes down, more and more UV rays can pass through the atmosphere and reach the surface and can cause more skin cancer and cataracts in older people.

Here we are looking at the ozone science. How the ozone is produced and how the ozone is destroyed. In the first step, the oxygen molecules are photolyzed or converted by the UV rays that are coming from the sun into two oxygen atoms; nascent oxygen atoms. Oxygen atoms are very, very reactive, and they react with another oxygen molecule and form ozone, O3. Ozone and oxygen atoms are continually being interconverted as rays break the ozone and turns into nascent oxygen and oxygen molecules. And the oxygen atom again reacts with the oxygen molecules, forms ozone. Our activities, which are producing the CFC’s and liberating into the atmosphere, they are going, and these chlorine atoms are destroying the ozone molecules in addition to the natural process of formation and destruction. That is what is causing the reduction in the concentration of ozone in the stratosphere and when the concentration goes down below certain levels, like 220 Dobson units, we call that ozone hole. Ozone hole does not mean that there is a big hole up there, but what it means is that the concentration is below a certain level.