1.0 Introduction
Air pollution is a significant risk factor for multiple health conditions including respiratory infections, heart disease and lung cancer, according to WHO. The health effect caused by air pollution may include difficulty in breathing, wheezing, coughing and aggravation of existing respiratory and cardiac conditions. These effects can result in increased medication use, increased doctor or emergency room visits, more hospital admissions and premature death. The human health effects of poor air quality are far reaching but principally affect the body's respiratory system and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health status and genetics. The most common sources of air pollution include particulate matter, ozone, nitrogen dioxide and sulphur dioxide. Both indoor and outdoor air pollution have caused approximately 3.3 million deaths world wide. Children aged less than five years that live in developing countries are the most vulnerable population in terms of total deaths attributable to indoor air pollution.
The World Health Organization states that 2.4 million people die each year from causes directly attributable to air pollution with 1.5 million of these deaths attributable to indoor air pollution. Epidemiological studies suggest that more than 500,000 Americans die each year from cardiopulmonary disease linked to breathing fine particle air pollution. A study by the University of Birmingham has shown a strong correlation between pneumonia related deaths and air pollution from motor vehicles. World wide, more deaths per year are linked to air pollution that to automobile accidents. Published in 2005 suggests that 310,000 Europeans die from air pollution annually. Causes of deaths include aggravated asthma, emphysema, lung and heart diseases and respiratory allergies. The US EPA estimates that a proposed set of changes in diesel engine technology could result in 12,000 fewer premature mortalities, 15,000 fewer heart attacks, 6,000 fewer emergency room visits by children with asthma and 8,900 fewer respiratory related hospital admissions each year in the United States.
The worst short term civilian population crisis in India was the 1984 Bhopal Disaster. Leaked industrial vapours from the Union Carbide factory, belonging to Union carbide, Inc U.S.A killed more than 25,000 people outright and injured anywhere from 150,000 to 600,000.
The United Kingdom suffered its worst air pollution event when the December 4 great smog of 1952 formed over London. In six days more than 4,000 died and 8,000 more died within the following months. An accidental leak of anthrax spores from a biological warfare laboratory in the former USSR in 1979 near Sverdlovsk is believed to have been the cause of hundreds of civilian deaths. The worst single incident of air pollution to occur in the United States of America occurred in Donora, Pennsylvania in late October, 1948, when 20 people died and over 7,000 were injured.
A new economic study of the health impacts and associated costs of air pollution in the Los Angeles Basin and San Joaquin Valley of Southern California shows that more than 3,800 people die prematurely (approximately 14 years earlier than normal) each year because air pollution levels violate Federal standards. The number of annual premature deaths is considerably higher than the fatalities related to auto collisions in the same area which average fewer than 2,000 per year.
Diesel exhaust (DE) is a major contribution derived particulate matter air pollution. In several human experimental chamber set up, DE has been linked to acute vascular dysfunction and increased thrombus formation. This serves as a plausible mechanistic link between the previously described association between particulate matter air pollution and increased cardiovascular morbidity and mortality.
Between 1948 and 1962, about eight air pollution episodes in December 1952 was the most significant Kiely (1997). Smoke concentration rose 50 times above the average limit and at the National Gallery visibility was poor enough for individuals not to see their own feet Anoop and Johnson (2003). An estimated excess death toll of 4000 occurred during the period, a threefold increase over the expected mortality rate for that time of the year. They said that most deaths were among infants and the elderly people.
Similarly episodes of severe air pollution in the United States and Belgium in those early days aroused public concern about the health effects of air pollutants increased public and parliamentary concern led to more effective legislation. in the United Kingdom subsequent Clean Air Acts of 1956 and 1968 and similarly the Clean Air Act of 1970 in the United States had considerably reduced air pollution from stationary sources, commerce and industry. Emission of smoke and Sulphur dioxide (SO2) fell dramatically. The historical perspective of traditional air pollutants continue to interest contemporary air quality researchers.
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