What is AIR pollution?

AIR POLLUTION?

Air pollution is a chemical, physical (e.g. particulate matter), or biological agent that modifies the natural characteristics of the atmosphere. The atmosphere is a complex, dynamic natural gaseous system that is essential to support life on planet Earth. Stratospheric ozone depletion due to air pollution has long been recognized as a threat to human health as well as to the Earth's ecosystems. Worldwide air pollution is responsible for large numbers of deaths and cases of respiratory disease. Enforced air quality standards, like the Clean Air Act in the United States, have reduced the presence of some pollutants. While major stationary sources are often identified with air pollution, the greatest source of emissions is actually made up by mobile sources, mainly the automobiles. Gases such as carbon dioxide, which contribute to global warming, have recently gained recognition as pollutants by some scientists. Others recognize the gas as being essential to life, and therefore incapable of being classed as a pollutant.


Sources of air pollution

Dust storm approaching Stratford, Texas

Using a controlled burn on a field in South Georgia in preparation for spring planting.
Anthropogenic sources (human activity) related to burning different kinds of fuel
"Stationary Sources" as smoke stacks of power plants, manufacturing facilities, municipal waste incinerators
"Mobile Sources" as motor vehicles, aircraft etc.
Combustion-fired power plants
Controlled burn practices used in agriculture and forestry management
Motor vehicles generating air pollution emissions.
Marine vessels, such as container ships or cruise ships, and related port air pollution.
Burning wood, fireplaces, stoves, furnaces and incinerators
Other anthropogenic sources
Oil refining, power plant operation and industrial activity in general.
Chemicals, dust and crop waste burning in farming, (see Dust Bowl).
Fumes from paint, hair spray, varnish, aerosol sprays and other solvents.
Waste deposition in landfills, which generate methane.
Military uses, such as nuclear weapons, toxic gases, germ warfare and rocketry.
Natural sources
Dust from natural sources, usually large areas of land with little or no vegetation.
Methane, emitted by the digestion of food by animals, for example cattle.
Radon gas from radioactive decay within the Earth's crust.
Smoke and carbon monoxide from wildfires.
Volcanic activity, which produce sulfur, chlorine, and ash particulates


Health effects

The World Health Organization thinks that 4.6 million people die each year from causes directly attributable to air pollution. Many of these mortalities are attributable to indoor air pollution. Worldwide more deaths per year are linked to air pollution than to automobile accidents.Published in 2005 suggests that 310,000 Europeans die from air pollution annually. Direct causes of air pollution related deaths include aggravated asthma, bronchitis, emphysema, lung and heart diseases, and respiratory allergies. The US EPA estimates that a proposed set of changes in diesel engine technology (Tier 2) 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 pollution crisis in India was the 1984 Bhopal Disaster. Leaked industrial vapors from the Union Carbide factory, belonging to Union Carbide, Inc., U.S.A., killed more than 2,000 people outright and injured anywhere from 150,000 to 600,000 others, some 6,000 of whom would later die from their injuries. The United Kingdom suffered its worst air pollution event when the December 4th 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. [1]
The health effects caused by air pollutants may range from subtle biochemical and physiological changes to 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. People who exercise outdoors, for example, on hot, smoggy days increase their exposure to pollutants in the air.

[edit] Greenhouse effect and ocean acidification
The greenhouse effect is a phenomenon whereby greenhouse gases, create a condition in the upper atmosphere causing a trapping of heat and leading to increased surface and lower tropospheric temperatures. The effect prevents the planet from severe cooling, and so benefits all living things. It shares this property with many other gases, the largest overall forcing on Earth coming from water vapour. Other greenhouse gases include methane, hydrofluorocarbons, perfluorocarbons, chlorofluorocarbons, NOx, and ozone. Many greenhouse gases, contain carbon, and some of that from fossil fuels.
This effect has been understood by scientists for about a century, and technological advancements during this period have helped increase the breadth and depth of data relating to the phenomenon. Mars has little atmosphere, and the little CO2 present is insufficient to prevent cooling, so the planet cannot support life. On Venus there is a massive runaway greenhouse effect, on Earth, scientists are studying the role of changes in composition of greenhouse gases from natural and anthropogenic sources for effect on climate change.
A number of studies have also investigated the potential for long-term rising levels of atmospheric carbon dioxide to cause slight increases in the acidity of ocean waters and the possible effects of this on marine ecosystems. However, carbonic acid is a very weak acid, and is utilized by marine organisms during photosynthesis