Pollutants and Emission Sources
A number of air pollutants can cause damage to health. Six major air pollutants (Carbon Monoxide, Lead, Nitrogen Dioxide, Ozone, Particulate Matter, and Sulfur Dioxide) have been identified as causing health effects at concentrations in the ambient air (the outside air we breathe) above thresholds established at levels known to be safe. These pollutants are referred to as "criteria pollutants" and a National Ambient Air Quality Standard (NAAQS) has been established for each based on health related criteria and data.
The following pages have information on the criteria pollutants, other air pollutants and emission sources:
Acid rain, which may damage lakes and streams, occurs when emissions of certain air pollutants react in the atmosphere to form acidic compounds that are then deposited on the earth's surface. The Clean Air Act limits the emissions of acid-forming pollutants from electric power plants by assigning each plant an emissions "allowance" that must be met through emissions reduction or purchase of emission "credits" from plants that have reduced emissions below their allowances.
Air toxics are those air pollutants that are known or suspected to cause cancer or other serious health effects. Air toxics can come from natural sources (e.g., radon gas coming up from the ground) or man-made sources such as motor vehicles and industrial processes. Examples include benzene (from gasoline), perchloroethylene, (from dry cleaners), and methylene chloride (used as a solvent and paint stripper).
Asbestos is an incombustible chemical-resistant, fibrous material used for fireproofing materials as well as insulation, building materials, brake linings, etc. Asbestos fibers in the ambient air pose a risk to human health in the form of cancer and other diseases. As such, asbestos is heavily regulated at the state and federal levels.
A Criteria Pollutant - Carbon Monoxide is produced primarily by motor vehicles. It can reduce a person's ability to think clearly, and causes visual impairment and headaches if high enough concentrations are experienced for a long period of time.
Chlorofluorocarbons are various compounds used as aerosol propellants, solvents, and refrigerants. Such compounds when released into the atmosphere contribute to the breakdown of the stratospheric ozone layer which shields the earth's surface from dangerous solar ultraviolet radiation.
The greenhouse effect is a natural phenomenon that occurs when certain gases in the atmosphere, especially water vapor, carbon dioxide and methane, cause the Earth's surface to heat up more than it otherwise would, thereby maintaining a global average temperature warm enough to support a rich variety of life. Global warming occurs when the amounts of carbon dioxide and other such gases in the atmosphere increase beyond natural levels, thereby intensifying the greenhouse effect.
A Criteria Pollutant - Lead can affect the central nervous system and lead to anemia. The young and the elderly are most susceptible to the harmful effects of lead.
Reactive, inorganic mercury is emitted to the atmosphere from various sources and then deposited on the earth's surface. Some of the deposited mercury ends up in wetlands, lakes, and streams where bacteria convert it into methylmercury, a toxic form that builds up (bioaccumulates) in the tissues of animals at each link in the food chain. In some cases, mercury accumulates in sport fish to levels that would be toxic if eaten by humans over a prolonged period of time or by the wildlife that prey upon those fish.
Mobile source emissions account for almost a third of the air pollution in the United States. These emissions contribute to the formation of ozone, an air pollutant considered to be a major air quality problem. Accordingly, new federal standards for Mobile Sources have been enacted to address this problem.
A Criteria Pollutant - Ozone is noteworthy in two aspects. High in the atmosphere (in the stratosphere), a natural layer of ozone surrounds the earth and protects the surface from harmful ultraviolet radiation from the sun ("good" ozone). It has been found that man-made gases, especially chlorofluorocarbons (CFCs), have depleted the stratospheric ozone layer, leaving the earth and its population more vulnerable to the adverse health effects of excess ultraviolet radiation (e.g., increased skin cancer, cataracts, and weakened immune systems).
At the surface, high levels of ozone are associated with urban smog ("bad" ozone). Breathing this ozone can result in damage or irritation to the lungs. Ozone builds up near the ground through a series of chemical reactions involving man-made emissions of volatile organic compounds and nitrogen oxides. Nitrogen oxides are produced by motor vehicles, off-road engines and fuel-burning facilities such as power plants. Volatile organics are produced by natural sources, such as trees, as well as by solvents and fuels that readily evaporate.
A Criteria Pollutant - Particle Pollution is the general term used for a mixture of solid particles and liquid droplets found in the air. This pollution, also known as particulate matter, is made up of a number of components, including acids (such as sulfates and nitrates), organic chemicals, metals, soil or dust particles and allergens (such as fragments of pollen or mold spores).
Vehicles, gasoline and diesel powered, which emit smoke from the exhaust pipe contribute to the degradation of ambient air quality. Florida Statutes prohibit the operation of such vehicles and provide penalties for violations.
Air pollutants are emitted into the atmosphere from stationary, area, and mobile sources. Stationary sources include utility, industrial, institutional and commercial facilities. Examples are electric power plants, phosphate processing plants, pulp and paper mills, and municipal waste combustors. Area sources include many individually small activities such as gasoline service stations, small paint shops, consumer solvent use, and open burning associated with agriculture and forest management activities.
A Criteria Pollutant - Sulfur Dioxide (SO2) is produced by power plants and industries that burn fossil fuels that contain sulfur, such as coal and oil, and by the phosphate industry through its production of sulfuric acid.
Last updated: May 22, 2013