Ozone is constantly produced and destroyed in a natural cycle. Ozone production and destruction are balanced, ozone levels remain stable. Large increases in stratospheric chlorine and bromine have upset the balance of the ozone. In effect they have added siphon downstream, removing ozone faster than natural ozone creations can keep up. Therefore ozone level falls. It is essential to know about ozone and its circulation in environment to maintain a proper environment al balance. This is also essential knowledge for everybody studying the biology at various levels.