Air pollution occurs when specific compounds in the atmosphere reach a state where exposure to humans and/or the ecosystem causes damage. (Slanina 2006). Although many sources of pollution are natural components of air, when occurring in large quantities these pollutants can be environmentally harmful. Earth’s atmospheric composition is 78 percent nitrogen and 21 percent oxygen. The remaining one percent is composed of gases such as water vapor, carbon dioxide, methane, nitrous oxide, and ozone (Lide 1997). Natural processes such as volcanic eruptions, decay of organic matter, and wildfires generate minute quantities of air pollution (Slanina 2006). However the amount created by human activities is far more substantial and still growing.
The six most common air pollutants are ground-level ozone, particulate matter, carbon monoxide, nitrogen dioxide, sulfur dioxide, and lead (EPA 2007). These pollutants manifest themselves primarily in the environmental problems of acid rain, smog, and climate change. Pollutants can enter the atmosphere through processes including the burning of fossil fuels, waste incineration, chemical usage, and agriculture production (EPA 2007).
The environmental problems caused by air pollution have serious ramifications. Acid rain, or low-pH precipitation in the atmosphere, is caused by emissions of sulfur and nitrous oxides from motor vehicles and industry. Acid rain expedites the deterioration of manmade structures and quickly wears away rock formations and other natural landmarks. Additionally, acid rain causes fish kills and other detrimental effects to aquatic environments by gradually lowering the pH of freshwater and estuarine environments (U.S. Geological Survey 1997).
Risk of cardiovascular disease has increased significantly in correlation with rising quantities of air pollutants. The World Health Organization (WHO) research shows that worldwide, approximately 4.6 million deaths per year are caused by air pollution-related problems (Kirby 2004). According to a recent University of Washington study reported by the BBC, just a 10-microgram increase in pollution areas correlates with a 76 percent increase in deaths from heart disease or stroke (BBC 2007). High pollution levels have also been linked to premature births, low birth weight, and severe cardiovascular birth defects (EPA 2007).
Due to the nature of global weather patterns, pollution released into the air in one country is often transported across boundaries and negatively impacts other countries. Increasing output of pollutants caused by human activities has led to higher global atmospheric concentrations of methane, carbon dioxide, nitrous oxide, HFCs (hydrofluorocarbons) and PFCs (perfluorocarbons). These are all gases that contribute to global warming (Schmid 2006). The air pollutants which cause acid rain also tend to cross national borders and cause harm to ecosystems located in countries where the pollution did not originate (Wellburn 1988). Additionally, trade between developed and developing countries often encourages increased air pollution in the latter as developing countries such as China pollute the atmosphere as it satiates other countries’ needs for inexpensive goods (Kahn 2007).
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