Depletion of Ozone Layer:
Since the last decade or so, there is concern about the possible reduction in the ozone layer surrounding the earth. Now the question arises, what had led to the depletion of this layer. The reasons are many. The foremost is the widespread usage of chlorofluorocarbons. These are gases which readily liquify when compressed. This makes them useful as refrigerants, propellants in aerosol cans, and in plastic foams. Chlorofluorocarbons are very stable and accumulate in the atmosphere, where they react with ozone. Nitrogen oxides also play a significant role in ozone destruction. It is being felt that the introduction of more nitrogen oxides into the upper atmosphere by jet planes flying there could decrease the ozone to dangerously low level. The fear is that chlorofluorocarbons will deplete the ozone layer and allow more ultraviolet radiations to reach the earth's surface. An increased level of ultraviolet radiations would cause more skin cancer, affect crops, interfere with oxygen cycle and even distoti weather patterns.