Automobile emissions (Encyclopedia of Environmental Issues, Revised Edition)
Automobile emissions create ongoing and potentially dangerous environmental problems when gases and particulates are released into the atmosphere at a rate that exceeds the capacity of the atmosphere to dissipate or dispose of them. Motor vehicle emissions are a major component of the smog that blankets such urban areas as Los Angeles, California, and Denver, Colorado. The emissions produced by a motor vehicle consist of exhaust (the by-products of incomplete gasoline or diesel fuel combustion) and fuel that evaporates from the vehicle’s fuel tank, engine, and exhaust system during operation, cooldown, and fueling.
Vehicle exhaust contains several problematic compounds. Carbon monoxide, produced by incomplete combustion, reduces the flow of oxygen in the bloodstream. Hydrocarbons, another product of imperfect combustion, are often toxic or carcinogenic. Nitrogen oxides, which are formed when combusting fuel reacts with oxygen in the air, contribute to the formation of acid rain and fine particles that can harm the lungs when breathed in. Together, hydrocarbons and nitrogen oxides react with the heat of sunlight to produce a hazy brown mixture of secondary pollutants. Notable among these pollutants is ground-level ozone, which irritates the eyes and causes damage to the respiratory system. (Nitrogen oxides also readily create ozone by reacting with naturally occurring hydrocarbons produced by trees.) Other secondary pollutants formed by...
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Impacts on Health and Environment (Encyclopedia of Environmental Issues, Revised Edition)
Environmental problems associated with automobile emissions include deleterious effects on many forms of agriculture and natural forests, reduction in visibility, and damage to metals, building materials such as stone and concrete, rubber, paint, textiles, and plastics. Automobile emissions cause lung and eye irritation, coughing, chest pain, shallow breathing, and headaches. Automobile-produced air pollution is also a factor contributing to allergies, asthma, emphysema, bronchitis, lung cancer, heart disease, and negative psychological states. Carbon monoxide quickly combines with blood hemoglobin and impairs oxygen delivery to the tissues, particularly in children and the elderly, causing heart and lung problems. Vehicular emissions and other sources of air pollution cost Americans billions of dollars each year in health care and related expenses.
The increased rate and depth of breathing during physical exertion exposes delicate lung tissues to more polluted air. Research indicates that exercise near a busy freeway may be more harmful than beneficial to the body. At the 1984 Summer Olympics in Los Angeles, the evening rush-hour start of the men’s marathon coincided with a stage 2 California health advisory alert, drawing criticism that the organizers of the event were more interested in commercial revenues than in the safety of the athletes and spectators. Later Olympic events were postponed during...
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Efforts to Reduce Emissions (Encyclopedia of Environmental Issues, Revised Edition)
Studies in cities such as London, England, have shown that major improvements in air quality can be achieved in less than ten years in urban areas with favorable climatic conditions through the use of more combustion-efficient engines and cleaner-burning fuels . In the United States, the 1970 amendments to the 1963 Clean Air Act (CAA) introduced automobile emissions standards for hydrocarbons, carbon oxides, and nitrogen oxides and ambient air-quality standards for six pollutants—carbon monoxide, sulfur oxides, nitrogen oxides, particulates, ozone, and lead—to protect human health and the environment. Through the CAA and its amendments of 1970, 1977, and 1990, the Environmental Protection Agency (EPA) has established increasingly stringent emissions-control policies for motor vehicles.
Although the EPA sets pollution standards for vehicles, vehicle manufacturers determine how they will meet those standards. Improved engine design, recirculation of exhaust gas to reduce nitrogen oxides, improved evaporative emissions controls, and computerized diagnostic systems have all led to a decline in polluting emissions. One of the most important milestones in the reduction of hydrocarbon and carbon monoxide emissions was the advent of the catalytic converter in 1975. Because lead impedes the catalyst that reduces emissions, unleaded gasoline became widely available at the same time. Ultimately, leaded gasoline was...
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Further Reading (Encyclopedia of Environmental Issues, Revised Edition)
Godish, Thad. Air Quality. 4th ed. Boca Raton, Fla.: Lewis, 2004.
Griffin, Roger D. Principles of Air Quality Management. 2d ed. Boca Raton, Fla.: CRC Press, 2007.
Hilgenkamp, Kathryn. “Air.” In Environmental Health: Ecological Perspectives. Sudbury, Mass.: Jones and Bartlett, 2006.
Jacobson, Mark Z. Atmospheric Pollution: History, Science, and Regulation. New York: Cambridge University Press, 2002.
McCarthy, Tom. Auto Mania: Cars, Consumers, and the Environment. New Haven, Conn.: Yale University Press, 2007.
Rajan, Sudhir Chella. The Enigma of Automobility: Democratic Politics and Pollution Control. Pittsburgh: University of Pittsburgh Press, 1996.
U.S. Environmental Protection Agency. The Plain English Guide to the Clean Air Act. Research Triangle Park, N.C.: Office of Air Quality Planning and Standards, 2007.
(The entire section is 110 words.)