Wednesday, March 2, 2011

Air pollution

Air pollution is not a problem; it has been around for centuries. Over three centuries ago, the noted scientist and diarist John Evelyn described with great accuracy many of the effects of the air pollution arising from the combustion of coal, reduction in sunshine ,morbidity and mortality from respiratory ailments, dust fall, corrosion of materials.
According to WHO, air pollution may be defined as follows:
"Substances but into air by the activity of mankind into concentration sufficient to cause harmful to his health, vegetables, property, or to interface with the enjoyment of his property."
In it's broad context, air pollution may exist  in three distinct categories:
  1. Personal air pollution: It refers to exposure to dust, fumes and gases to which an individual exposes himself when he indulges in cigarette, cigar or pipe smoking.
  2.  Occupational air pollution: It represents the type of exposure of individuals to potentially harmful concentrations of aerosols, vapors and gases in their working environment.
  3. Community air pollution: It represents the most complex of the three varieties since it involves a varied assortment of pollution sources and contaminants, meteorological factors, and a wide diversity  of adverse social, economic and health effects. 
Notable air pollution episodes:
There are some notable episodes in history. The description is given below:
1.      The London smog: Historically, the longest record of intermittent air pollution problems belongs to the city of London, England. the notorious pea-soup fogs become especially offensive when mixed with coal smoke. The word smog (smoke & fog) was coined to describe this foul condition. Sir Hugh E.C. Beaver, chairman of the Government Committee of enquiry into the nature, causes, effects of air pollution, says in his review of the growth of public opinion: It strikes a sympathetic chord, I think, to learn that 700 years ago almost to a year the then Queen of England moved out of the city to Nottingham where she was residing because of the insufferable smoke; and that some 300 years later the brewers of Westminster offered to use wood instead of coal because4 of queen of Elizabeth's allergy to coal smoke. In 1661, John Evelyn got published his well known pamphlet, "funifugium" or The Inconvenience of the Air and Smoke of London Dissipated." His major recommendation had been the removal of all smoke-producing plants from London. But in December 1952, truly a major air pollution disaster occurred. The smog lasted 5 days and caused 4000 deaths among the old, the infirm, and those with respiratory diseases. Almost exactly ten years later, December 3 to 7, 1962, London experienced another black fog, with 340 excess deaths.

2.      The Donora smog: Donora Pennsylvania (1950 population-12,186), has been an industrial town on the banks of the Monogahela river about 30 miles south of the heart of Pittsburgh. The major industrial installations were a steel and wire mill, a zinc smelter, and a sulfuric acid plant. During a particularly calm and meteorologically stable period from October 27 to 31, 1984, air pollutants accumulated, and because of this many persons were hospitalized and 20 died.As in the London  smog of 1952, the causative agent of the deaths illness could never be determined incontrovertibly, but in both instances sulfur compounds were present in the air in abnormally high quantities.

3.      Meuse Valley, Belgium: A strong atmospheric inversion got settled over the Meuse valley on December 1, 1930 and remained until December 5. effluents from the several factories in the Valley, chiefly oxides, of sulfur, various inorganic acids and soot were then trapped in the stable atmosphere. Sixty-three persons died, and several hundred others became ill.

4.      Pittsburgh, Pennsylvania: Prior to 1948 the nickname, “Smoky City", had been appropriate for Pittsburgh. A black pall of smoke, and soot often turned into night, blackened the brightest buildings in a few months, and made washday a nightmare, finally, the activity of the civic-minded Allegheny Conference on Community Development caused a smoke-control ordinance that dramatically changed the condition of atmosphere. The change resulted largely from regulations prohibiting the sale, transportation and use of high volatile solid fuels except where adequate mechanical stoking equipment is available.Smoke reduction between 1945 and 1953 had been estimated at 70% by the Department of Public Health.

5.      Bhopal MIC Gas Tragedy: The MIC gas leak in Bhopal in 1984 has been regarded the worst industrial accident which is related to air pollution. Around 2,00,000 Bhopal residents were affected by the leak of poisonous MIC gas from Union Carbide Pesticide plant there. Almost 5000 people were killed and doctors estimated that some 50,000 people have been seriously affected and many go blind. The full form of MIC is Methyl-iso-cyanate. It is a toxic gas used in the manufacture of pesticides. It reacts quickly with water and causes the lungs to swell and eyes to develop cataract. Many died in Bhopal because their lungs had failed with fluid. Bhopal's victims continue to die. Out of every 3 children born to women who were pregnant on the night of the disaster, only one survives. Out of 1,350 new born babies, 16 were physically deformed and 60 premature births. The vegetation in an area of 3.5 sq. km. around the Union Carbide factory at Bhopal was seriously affected.

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