CHEMISTRY - Air Pollution

An addition of undesirable materials into the atmosphere either due to the natural phenomena or due to the human activity on the earth which adversely affect the quality of the air and hence affect the life on the earth. This phenomenon is known as Air pollution.
When we talk about an air pollution, we mean the pollution of air upto a height of about 50 km above the surface of the earth. This part of the air is called homosphere because the different constituents present in it form a homogeneous mixture.
The composition of pure dry air is as follows :-
Nitrogen - 78.10% , Oxygen - 20.95% , Ar. - 0.93% , Corbondioxide - 0.032%
Air has never been pure right from the day the man started burning fuel. The oxides of corbon, nitrogen, and sulphur become pollutants if their amount exceeds a certain limit ( called Tolerance Limit )

<b> Sources of Air Pollution :-</b> The main sources of air pollution may be classified into two categories as follows :-
1. Natural Sources :- Thesources which occur due to natural process. Few example are :-
* Volcanic eruption emitting poisonous gases like CO , Sulphur dioxide etc.
* Forest fires and coal-refuse fires.
* Vegetatiin decay.
* Pollen grains of flowers.

2. Sources due to human activity :- These sources occur due to the human activity is known as Sources due to human activity. Few examples are :-

* Burning Of Fossil Fuels :- Which produce some poisonous gases as by - products such as CO, oxides of nitrogen etc.
* Combustion of gasoline in the automobiles:- e.g. cars, scooter, bus, trucks etc. They emit out poisonous gases like CO, oxides of nitrogen etc.
* Increase in population :- This is one of the major cause of pollution. More, the population, more are the needs, greater are the unnatural method adopted which disturb the balance or equilibirium of the atmosphere.
* Deforestation :- Man has been cuttin trees indiscriminantely to meet his needs. This has resulted in increase in the precentage of carbon dioxide and decrease in the precentage of oxygen in the air.
* Agricultural Activities :- The pesticides added to the soil or the sprays done over the crops are carried by the wind to different parts of the town where they give a foul smell and affect the health of animals and human beings.
* Wars :- The nuclear weapons used during wars emit out radiations which adversely affect the health and prove to be fatal.
* Fast Industrialisation :- In the last few years, the number of industries in different parts of the world and their production has increased manifold. These include paper mills, sugar mills, rubber and plastic industries.

<b>Effects of Air Pollution :-</b>
* Effects on Plants.
* Effects on Materials.
* Effects on Climate.
* Effects on Human Beings.