depletion of ozone layer

            
            
            
             The ozone layer diminishes more each year.
             polar ozone depletion (commonly called the ozone hole) gets .
             larger, additional ultraviolet rays are allowed to pass through. .
             These rays cause cancer, cataracts, and lowered immunity to .
             diseases.1 What causes the depletion of the ozone layer?.
             In 1970, Crutzen first showed that nitrogen oxides produced .
             by decaying nitrous oxide from soil-borne microbes react .
             catalytically with ozone hastening its depletion. His findings .
             started research on "global biogeochemical cycles" as well as the .
             effects of supersonic transport aircraft that release nitrogen .
             oxide into the stratosphere.2 .
             In 1974, Molina and Rowland found that human-made .
             chlorofluorocarbons used for making foam, cleaning fluids, .
             refrigerants, and repellents transform into ozone-depleting .
             agents.3.
             .
             Chlorofluorocarbons stay in the atmosphere for several .
             decades due to their long tropospheric lifetimes. These compounds .
             are carried into the stratosphere where they undergo hundreds of .
             catalytic cycles with ozone.4 They are broken down into chlorine .
             atoms by ultraviolet radiation.5 Chlorine acts as the catalyst .
             for breaking down atomic oxygen and molecular ozone into two .
             molecules of molecular oxygen. The basic set of reactions that .
             involve this process are:.
             Cl + O3 -->ClO + O2 and.
             ClO + O -->Cl + O2.
             The net result:.
             O3 + O -->2O2.
             Chlorine is initially removed in the first equation by the .
             reaction with ozone to form chlorine monoxide. Then it is .
             regenerated through the reaction with monatomic oxygen in the .
             second equation. The net result of the two reactions is the .
             depletion of ozone and atomic oxygen.6.
             Chlorofluorocarbons (CFCs), halons, and methyl bromide are a .
             few of the ozone depletion substances (ODS) that break down ozone .
             under intense ultraviolet light. The bromine and fluorine in .
             these chemicals act as catalysts, reforming ozone (O3) molecules .