Air Pollution and Pollutants

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Air pollution

Air pollution occurs when the air contains gases, dust, fumes or odour in harmful amounts. That is, amounts which could be harmful to the health or comfort of humans and animals or which could cause damage to plants and materials.

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Causes of air pollution

The main causes of air pollution are as follows:
(a) Exhaust from Automobiles: Most of the automobiles use fossil fuels. Burning of fossil fuel releases carbon dioxide and carbon monoxide. Carbon dioxide is a greenhouse gas. Carbon monoxide is a poisonous gas even at low concentrations.
(b) Exhaust from Factories and Power Plants: Coal is the main fuel being used in factories. Burning of coal produces carbon dioxide and oxides of sulphur. Oxides of sulphur and nitrogen form acid rain when they mix with rainwater. Acid rain is harmful for living beings and also for buildings and monuments.
(c) Chlorofluorocarbons (CFCs): These are compounds of carbon and halogens and are used as refrigerant. These are also used in pressurized cans. Excess level of CFCs in the atmosphere damages the ozone layer. Ozone layer works like a shield and prevents the harmful ultraviolet radiations from reaching up to the living beings. Any damage in the ozone layer can be very harmful.
(d) Suspended Particulate Matters (SPMs): Some fine particles remain suspended in the air. These are called suspended particulate matters. Stone quarries and various other factories contribute to SPMs.

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Types of air pollution

The air pollution are basically of two types:
  • Gaseous pollution
  • Particulate pollution

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Types of air pollution according to origin and source

According to origin
  • Primary pollutants
  • Secondary pollutants
According to source
  • Natural
  • Man made

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Natural sources of air pollution

Natural sources of sulphur dioxide include release from volcanoes, biological decay and forest fires. Natural sources of nitrogen oxides include volcanoes, oceans, biological decay and lightning strikes. Ozone is a secondary photochemical pollutant formed near ground level as a result of chemical reactions taking place in sunlight.

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Man-made sources of air pollution

Man is responsible for most of the world's air pollution, both indoors and outdoors. Everything from smoking a cigarette to burning fossil fuels tarnishes the air we breathe and potentially causes health problems as minor as a headache to as harmful as respiratory, lung and heart disease.