General Knowledge



Pollution is the contamination of material particles of energy into the natural environment. It causes adverse effects on the ecosystem.

Types of Pollution
» Air Pollution
» Water Pollution
» Soil Pollution

Air Pollution

It occurs when any harmful gases, dust, smoke enters into the atmosphere and make it difficult for plants, animals, and humans to survive. Common respiratory diseases such as asthma and bronchitis can occur.

Water Pollution

It is due to the presence of foreign substances like sewage, algae, and soluble salts in water.

It can also be due to the presence of metals in water. This pollution causes the following diseases.

Metal Disease
Chromium and Arsenic Cancer
Cadmium Itai-itai disease
Mercury Minamata disease

For a healthy aquatic life, dissolved oxygen (DO) is 5-6 ppm.

For clean water, BOD (biochemical oxygen demand) is less than 5 ppm, while for highly polluted waer, it is 17 ppm or more.

Soil Pollution

It is an alteration in soil. It is caused by pesticides like insecticides (e.g., DDT, BHC, etc.), herbicides (e.g., sodium chlorate), and fungicides (e.g., organomercury compounds).