Connecticut's Management of Toxic Air Pollutants
Air Toxic Pollutants Sources
There are many sources of toxic air pollutants in Connecticut. These sources can be roughly grouped into four categories or sectors:
Major sources of air toxics are stationary sources that emit or have the potential to emit 10 tons or more per year of any one of the 188 air toxics listed in the 1990 Clean Air Act Amendments (Act), or 25 tons or more per year of combined air toxics. Examples of major sources are chemical plants, large printing and coating operations, pharmaceutical manufacturing plants, and waste incinerators. These sources emit air toxics through various means, including emissions stacks and vents, fugitive process emissions, equipment leaks, material transfer and handling, or accidental releases. In 1990, the EPA estimated that major sources emit 30% of all man-made air toxic emissions in the United States. However, due to several factors, including new regulations, process changes and economic factors, the latest information from 1999 indicates that only 6% of emissions of air toxic pollutants are from major sources.
Area sources of air toxics are stationary sources smaller than major sources, which emit less than 10 tons per year of any single air toxic or less than 25 tons per year of combined air toxics. Area sources include dry cleaners, gas stations, small print shops, auto body shops, electroplaters, and small manufacturers. Area sources also include consumer products in homes and offices such as cleaners, pesticides, paints, and glues. Although emissions from each area source may be relatively small, the collective emissions of area sources can create significant health risks, particularly if a large number of area sources are located in populous areas or clustered in a small area. In 1990, the EPA estimated that area sources emit 31% of all man-made air toxic emissions in the United States. Estimates from 1999 show that approximately 30% of air toxics are emitted from area sources.
Mobile sources include on-road vehicles such as automobiles, trucks, and buses and non-road equipment such as construction equipment. Mobile sources emit toxic air pollutants through the incomplete combustion of fuel and through the evaporation of fuel. Despite great gains in fuel economy and the efficacy of air pollution control equipment over the past twenty years, the EPA estimated in 1990 that mobile sources emit 39% of all man-made air toxic emissions in the United States. However, estimates based on 1999 information indicate that 64% of toxic air pollutant emissions originate from mobile sources, 38% from on-road and 26 % from non-road.
Natural sources of air toxics are diverse and numerous. For example, forest fires produce air toxics, such as particulates and volatile organic compounds. Another example is radon, a naturally occurring radioactive gas which comes from rocks containing uranium. Radon can pose health risk if it accumulates indoors within structures.
Content Last updated November 2005