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Tuesday, 26 February 2008 |
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With the boom in population and industrial growth, the need for power has increased manifold. Nearly 73% of India’s total installed power generation capacity is thermal, of which 90% is coal-based generation, with diesel, wind, gas, and steam making up the rest. Thermal power generation through coal combustion produces minute particles of ash that causes serious environmental problems. Commonly known as fly ash, these ash particles consist of silica, alumina, oxides of iron, calcium, and magnesium and toxic heavy metals like lead, arsenic, cobalt, and copper. The 80-odd utility thermal power stations in India use bituminous coal and produce large quantities of fly ash. According to one estimate, up to 150 million tonnes of fly ash will be produced in India in the year 2000, primarily by thermal power plants and, to a lesser extent, by cement and steel plants and railways. This poses problems in the form of land use, health hazards, and environmental dangers. Both in disposal and in utilization utmost care has to be taken to safeguard the interest of human life, wild life, and such other considerations. The prevalent practice is to dump fly ash on wastelands, and this has lain to waste thousands of hectares all over the country. To prevent the fly ash from getting airborne, the dumping sites have to be constantly kept wet by sprinkling water over the area. The coal industry in USA spends millions of dollars on lining fly ash dumping grounds. But in India, these sites are not lined and it leads to seepage, contaminating groundwater and soil. It lowers soil fertility and contaminates surface and ground water as it can leach into the subsoil.
When fly ash gets into the natural draining system, it results in siltation and clogs the system. It also reduces the pH balance and portability of water. Fly ash interferes with the process of photosynthesis of aquatic plants and thus disturbs the food chain. Besides, fly ash corrodes exposed metallic structures in its vicinity. In Delhi, the problem of fly ash is particularly severe as three power stations are located here. Being very minute, fly ash tends to remain airborne for a very long period leading to serious health problems as the airborne ash can enter the body. It causes irritation to eyes, skin, and nose, throat, and respiratory tract. Repeated inhalation of fly ash dust containing crystalline silica can cause bronchitis and lung cancer. |
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Last Updated ( Thursday, 03 July 2008 )
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Tuesday, 26 February 2008 |
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The effects of smog on human health were evident, particularly when smog persisted for several days. Many people suffered respiratory problems and increased deaths were recorded, notably those relating to bronchial causes. A haze of dense harmful smog would often cover the city of London. The first smog-related deaths were recorded in London in 1873, when it killed 500 people. In 1880, the toll was 2000. London had one of its worst experiences with smog in December 1892. It lasted for three days and resulted in about 1000 deaths. London became quite notorious for its smog. By the end of the 19th century, many people visited London to see the fog. Despite gradual improvements in air quality during the 20th century, another major smog occurred in London in December 1952. The Great London Smog lasted for five days and resulted in about 4000 more deaths than usual. In response to the Great London Smog, the government passed its first Clean Air Act in 1956, which aimed to control domestic sources of smoke pollution by introducing smokeless zones. In addition, the introduction of cleaner coals led to a reduction in sulphur dioxide pollution. In the 1940s, severe smog began covering the city of Los Angeles in the USA.
Relatively little was done to control any type of pollution or to promote environmental protection until the middle of the 20th century. Today, smoke and sulphur dioxide pollution in cities is much lower than in the past, as a result of legislation to control pollution emissions and cleaner emission technology.
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Last Updated ( Thursday, 03 July 2008 )
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Thursday, 14 February 2008 |
The freshness of the air in one's environment has a most fundamental and direct impact on the quality and length of one's life. Air is more a necessity of life than either food or water.
Imagine you live in a city where a gray-brown noxious haze of smog permeates the streets in your district. Imagine that these streets are filled with jam-packed traffic, a slow moving assembly of automobiles which blow out unhealthy exhaust fumes of carbon monoxide and other harmful chemicals. You cover your nose and mouth with a handkerchief to avoid excess exposure to dust and chemical particulates in the air. The air is not pleasant to inhale in deeply, and it gives you breathing trouble, making you co ugh and wheeze. In addition, your eyes water, your nose runs, and you have headaches and irritated eyes regularly when you are outdoors. As you walk on a street in this particular city on a weekday afternoon, a jogger passes by you wearing a face mask, an d you observe children playing in a nearby school, inside a giant glass bubble to shield them from the city air.  |
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Last Updated ( Thursday, 03 July 2008 )
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Urban Air Quality 
