Ozone breaks down in the ozone layer in the following major ways: * N2O* encounters water vapor, and can no longer help form ozone. * Ozone absorbs UV-C or UV-B and most of it will break back down to oxygen. * Ozone has a natural half-life, and decays spontaneously with time and temperature back to oxygen. * Ozone encounters water vapor, and forms hydrogen peroxide. * Ozone encounters a photocatalyst (like CFC, HCFC, Halon), and is converted back to oxygen.
CFCs, HCFCs, and Halon:
The ozone layer is destroyed by CFC's, chlorofluorocarbons, that are used as a propellant in aerosol cans, and refrigerants in older cars and refrigerators. When Chlorofluorocarbons (Freon and other CFCs) and Bromofluorocarbons (Halons) they became popular refrigerants and fire fighting agents. As the compounds were inert and thought to pose no damage to health or the environment they were handed without much consideration for losses. As a consequence the concentrations of these materials built up in the atmosphere. However (there's always a however) when the materials reached the stratosphere the were acted on by ultraviolet radiation and broke down releasing chlorine and bromine into the ozone layer. The ozone layer is the earth's ultraviolet shield. The chemistry is such that the chlorine and bromine attack the ozone, reducing it to ordinary oxygen which as no shielding effect from UV-B. The complex chemical reactions allow the chlorine and bromine to interact again and again with ozone molecules, until they eventually leave the ozone layer bonded to some other compound. Since the Montreal Protocol was developed to control and ban the use of these compounds the ozone layer has improved. But due to the long-lasting impact the problem will not be resolved totally for many years.
The ozone layer is strongly negatively affected by the presence of water vapor. Not only does it suppress the formation of...