(Online Cours) CAPF Assistant Commandant: Environment & Ecology - Pollution

Online Course for Central Armed Police Forces (CAPF) Exam (Assistant Commandant)

Environment & Ecology


Pollution can be defined as, “the act or process of polluting or the state of being polluted, especially the contamination of soil, water or the atmosphere by the discharge of harmful substances”. Accidental release of these substances in the environment lead to mass death. History witnesses these disasters today known in the form of episodes such as “London Smog” in 1912 and “Meuse River valley episode” in 1930. In 1948, the honour went to “Donora”, Pennsylvania when 40% of its population fell sick due to pollution from zinc smelter, steel mill and’ sulfuric acid plant. In 1952, London Smog struck again killing 4000 elderly and sick people. Soon simultaneous occurrences of severe air pollution in eastern United States, Western Europe and Japan turned into a world-wide episode. The fatal gas MIC (Methyl iso cyanate) killed over 2500 people in Bhopal in 1984.

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  • Pollution is the effect of undesirable changes in our surroundings that have harmful effects on plants, animals and human beings. This occurs when only short-term economic gains are made at the cost of long-term ecological benefits for humanity.

  • Pollutants include solid, liquid or gaseous substances present in greater than natural abundance, produced due to human activity, which have a detrimental effect on our environment.

  • An average human requires about 12 kg of air each day, which is nearly 12-15 times greater than the amount of food we eat. So, even a small concentration of pollutants in the air becomes more significant in comparison to similar levels present in food.

From an ecological perspective, pollutants can be classified as follows

Non-degradable pollutants: These cannot be degraded by natural processes. Once they are released into the environment they are difficult to eradicate and continue to accumulate; e.g., toxic elements like lead or mercury, and nuclear wastes.

Slowly-degradable or persistent pollutants: These are pollutants that remain in the environment for many years in an unchanged condition and take decades or longer to degrade; e.g., DDT (pesticides) and most plastics.
Degradable or non-persistent pollutants: These can be rapidly broken down by natural processes; e.g., domestic sewage, discarded vegetables, etc.

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