Name the gasecous pollutants present in the air and explain their formation.

Explanation

Substances which mix with air and affect the human beings, animals, plants and global temperature are called air pollutants.
Examples :
1) Oxides of Carbon : CO And `CO_2`
2) Oxides of Nitrogen : `N_2O` and NO
3) Oxides of Sulphur : `SO_2`
4) Ozone
5) CFCs : Chlorofluorocarbons
6) Methane and Butane
7) Smog
8) Metals : Lead, Mercury.
Air pollution : In cities 80% of air pollution is due to exhausts of automobiles. At peak times in cities the leavel of CO will be upto 50- 100 ppm. If it is inhaled, it causes adverse effects.
During the combustion of fossil fuels `NO, N_2O, NO_2 ` etc. are also released. When the level of these oxides is greater than 10 ppm, the plants cannot perform photosynthesis.
`SO_2` is released into the atmosphere during the burning of sulphur and roasting of sulphide ores. `SO_2` Causes respiratory diseases in human beings. It bleaches the green colour of the leaf apexes in plants to yellow colour and thus prevent photosynthesis process.
Chlorofluorocarbons when percolate into stratosphere cause depletion of ozone layer.
Harmful pesticides and biocides mix up with the are at their manufacturing units and pollute the air. They cause major health Hazards.