Sources of Air Pollution Emissions

Regional Patterns of Nitrogen Oxides Emissions

Nitrogen oxides emissions primarily result from combustion. Natural sources account for about 3% of the regional total.

Nearly half of regional NOx emissions are discharged by electric utilities burning coal, oil, or natural gas. Adding other combustion sources, including industrial boilers as well as smaller heating units in commercial and residential properties, account s for over half of regional NOx. The location of the largest of these sources is shown on the map on page 27.

Motor vehicles account for about 37% of NOx emissions. Because diesel fuel causes higher NOx emissions than gasoline, off-highway vehicles account for a larger proportion of NOx emissions in comparison to highway vehicles than is true for VOC emissions.

Sources: EPA (1996), EPA (1996), Air Quality Criteria for Ozone and Related Photochemical Oxidants.

1990 Mid-Atlantic Nitrogen Oxide Emissions

Map: Location of the Largest Utility and Industrial Sources of NOx

Regional Emissions of Volatile Organic Compounds

Natural emissions are a major source of volatile organic compounds in the Mid-Atlantic Region, accounting for over three-fourths of the total regional VOC emissions for 1990. For the US as a whole, EPA estimates that natural emiss ions of VOCs from vegetation are roughly three times as large as manmade emissions. Natural emissions are higher in the rural parts of the Mid-Atlantic Region, particularly in rural Virginia and North Carolina. (See Appendix B.)

VOC emissions from human activity are also substantial, particularly in the more urbanized parts of the Region. Motor vehicle exhaust emissions and evaporation of gasoline and other petroleum products account for about 12% of total Mid-Atlantic VOC emiss ions. That is, over half of the manmade emissions of VOC are transportation related.

Sources: EPA (1996), EPA (1996), Air Quality Criteria for Ozone and Related Photochemical Oxidants.
EPA (1996), Emission Reports for Base 90, which can be found on the world wide web at

1990 Mid-Atlantic VOC Emissions

Map: Country-Level Anthropogenic VOC Emission Density for a Typical Summer Day

Map: Country-Level VOC Biogenic Emission Density for a Typical Summer Day

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