Of the three types of pollution, i.e. air, water and sound, the air pollution is the most dangerous because if the water is polluted one can avoid drinking it or treat it, but if the air is polluted, we cannot stop breathing. Air pollution is caused by mixing of pollutants like carbon monoxide, lead, smoke particles, sulphur, mercury and other harmful chemicals in the air.
Since the dawn of civilisation man has endeavored to make his life more and more comfortable by producing various types °f goods that satisfy his wants. Human desires are endless. People want more and more goods with better look, quality and duration. With the increase in population, the demand for goods and services goes on increasing. To satisfy their ever-increasing demand, more and more industries are being set up.
These industries use coal and petroleum as source of energy in the process of production. These factories continuously release smoke in the air. Some industries like leather tanning use various types of chemicals in large quantities which spread in the air molecules of the surrounding area.
Constant research and inventions also make it possible to produce various articles in large quantities by setting up more industries. The development has thus become environmentally, destructive. Goods are being produced not only for local consumption but also for export to other countries to earn valuable foreign exchange. The economists and other experts often suggest a shift from agriculture to industry in order to achieve faster development. Moreover, mechanization of farming with the use of tractors, combine harvesters, threshers and diesel pumps has brought pollution even in green belts.
The shift from agriculture to industry makes it necessary to clear the forests to establish more factories. As trees are natural purifiers of air, deforestation worsens the problem of pollution.
With the development of trade and business there has been a corresponding increase in the transportation system. With the building up of vast network of roads in almost every country, the number of vehicles has increased many times. Buses, trucks, cars, two-wheelers, and many other types of vehicles that run on petrol or diesel give out huge quantity of smoke in the air every day.
These smokes contain many harmful chemicals and vitiate the air. Big cities have been the most affected by air pollution because of presence of large number vehicles. The air in the metropolitan cities of Delhi, Kolkata, Mumbai and Chennai is so much polluted that many people suffer from diseases like asthma, cancer, eye burning, skin rashes, etc.
Another major cause of air pollution is the burning of wood and coal in household for cooking. The LPG gas is available in cities and towns. In rural areas, wood, coal and kerosene are the only source to make fire and cook food. The rural hearths are therefore another cause of air pollution. The problem is worsened with the fact that trees are being cut to get fire wood.
Forests are viewed by many as a great source to exploit for timber, medicinal herbs, resins, fruits, nut, flowers, rubber, gum and bark. Their value as natural air purifiers, homes of valuable wild life, maintenance of eco-systems, habitats of various species of animals and birds, savers from floods and soil erosion is being forgotten. With a sharp increase in the world population during the last half century, jungles have been cleared in large areas to bring more land under cultivation to get food security, to make housing colonies and to construct commercial buildings, roads and industries. This reckless cutting of trees has intensified the problem of air pollution.
Air pollution has led to the following major problems, the end results of which could be quite catastrophic. The protective ozone layer has been ruptured to expose people to the harmful effects of radiation.
The trapping of excessive greenhouse gases has led to global warming which threatens to dwindle the run¬off regime of glaciers, the natural storehouses of water, submerge the coastal areas due to rise in the water level of oceans, increase the altitude of snowline and change the climatic patterns jeopardizing the life of many species of animals and plants.
The underlying cause of all these hazards is over¬population that has exerted tremendous pressure on earth’s natural resources. Clean air and water were once considered inexhaustible and tree gifts of nature have now become rare commodities. Provision of pollution-free air and potable water has turned to be a challenge for many a country. It is said that if there is a Third World War, it will be over water.
The forest cover which was once taken to be a renewable source is now considered non¬renewable because in the changed climatic pattern, altered seasons and patterns of precipitation, increasing level of pollution, destruction of natural habitats, drastically decreasing table of underground water, the tree growth is not as fast and as healthy as it should be to replenish the jungles.
The air pollution has adversely affected the vegetation cover in many areas. It has been established that chemicals discharged into the air by tanneries destroy the crops. Owing to the change in climatic patterns and unfavourable conditions, the growth of new saplings has become slow and less luxuriant.
The reckless cutting of trees has not only aggravated the problem of air pollution but also created other hazards like causing floods, soil erosion, change in the rain pattern and other climatic changes which have adversely affected the flora and fauna of a region, destruction of natural habitats and fragile eco¬systems, disturbance in the food web and harming the biological diversity of the area.
Water is necessary for sustenance of all life on the earth. India ranks fifth in the world in potential water resources behind only the Republic of Congo, Russia, Canada and the USA. But, our water bodies like rivers, streams, ponds, tanks, lakes and wells have not been properly maintained. They are not only full of mud and silt but are further polluted by the release of harmful chemical industrial wastes and untreated sewerage water into them.