Air Pollution: Sources and Effects of Air Pollution

Some of the main sources and effects of air pollution are as follows:

Air pollution is the contamination of the air by noxious gases and minute particles of solid and liquid matter (particulates) in concentrations that endanger health.


The major sources of air pollution are transportation engines, power and heat generation, indus­trial processes and the burning of solid waste.


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Sources of Air Pollution:

The combustion of gasoline and other hydrocarbon fuels in automobiles, trucks and jet airplanes produces several primary pollutants such as nitrogen oxides, gaseous hydrocar­bons and carbon monoxide as well as large quantities of particulates, chiefly lead. In the presence of sunlight, nitrogen oxides combine with hydrocarbons to form a secondary class of pollutants, the photochemical oxidants, among them ozone and the eye-stinging peroxyacetylnitrate (PAN). Nitrogen oxides also react with oxygen in the air to form nitrogen dioxide, a foul-smelling brown gas.

In urban areas like Los Angeles, where transportation is the main cause of air pollution, nitrogen dioxide tints the air, blending with other contaminants and the atmospheric water vapour to produce brown smog. Although the use of catalytic converters has reduced smog-producing compounds in motor vehicle exhaust emissions, recent studies have shown that in doing so the converters produce nitrous oxide, which contributes substantially to global warming.

In cities, air may be severely polluted not only by transportation but also by the burning of fossil fuels (oil and coal) in generating stations, factories, office buildings and homes and by the incineration of garbage. The massive combustion produces tons of ash, soot and other particulates responsible for the grey smog of cities like New York and Chicago, along with enormous quantities of sulphur oxides. These oxides rust iron, damage building stone, decompose nylon, tarnish silver and kill plants. Air pollution from cities also affects rural areas for many miles downwind.


Every industrial process exhibits its own pattern of air pollution. Petroleum refiner­ies are responsible for extensive hydrocarbon and particulate pollution. Iron and steel mills, metal smelters, pulp and paper mills, chemical plants, cement and asphalt plants— all discharge vast amounts of various particulates. Uninsulated high-voltage power lines ionize the adjacent air, forming ozone and other hazardous pollutants. Airborne pol­lutants from other sources include insecticides, herbicides, radioactive fallout and dust from fertilizers, mining operations and livestock feedlots.

Effects on Health and the Environment:

Air pollution may possibly harm populations in ways so subtle or slow that they have not yet been detected. For that reason, research is now underway to assess the long-term effects of chronic exposure to low levels of air pollution—experiences of people to deter­mine how air pollutants interact with one another in the body with physical factors such as nutrition, stress, alcohol, cigarette smoking and common medicines. Another subject of investigation is the relation of air pollution to cancer.

Effects of Air Pollution on Health:

Air pollution has unhealthy effects on people, animals and plant life across the globe. Every time we inhale, we carry dangerous air pollutants into our bodies. These pollutants can cause short-term effects such as eye and throat irritation. More alarming, however, are the long-term effects such as cancer and damage to the body’s immune, neurological, reproductive and respiratory systems. Children, due to their size and the fact that they are in the process of developing, are at greater health-related risk.

The mechanisms by which air pollutants can cause serious adverse health effects are not fully understood. However, many possible mechanisms have been proposed.


The possible mechanism of air pollutants related to lung disease is that small particles penetrate the alveolar epithelium and cause lung inflammation. If an individual already has damaged lungs or lung disease, then increased inflammation as a result of air pollution will worsen their condition.

Air pollution can also cause heart attacks. Two potential mechanisms by which it does this have been proposed:

(i) Lung inflammation can lead to the release of chemicals from macrophages that cause changes in the clotting mechanism of the blood.

(ii) A neural reflex may be initiated by the irritant effects of air pollutants in the lung leading to changes in heart rhythm and rate.

Effects of Air Pollution on Environment:

Climate change on a global scale has been attributed to the increased emissions of CO2, a greenhouse gas. A global average temperature rise of only 1°C could have serious implications. Possible consequences include the melting of polar ice caps; an increase in the sea level; and increases in precipitation and severe weather events like hurricanes, tornadoes, heat waves, floods and droughts. Indirect effects include increases in infectious disease, weather-related deaths and food and water shortages. All these effects put a stress on ecosystems and agriculture, and threaten our planet as a whole.


Air pollution is not just a city problem.’ Many air pollutants are dispersed over areas hundreds of miles from their source where they affect many different ecosystems. These pollutants often remain toxic in the environment for a very long time where they continue to affect ponds, streams, fields and forests. Acid rain and global warming are the results of air pollution on the environment.

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