TABLE 74b Nitrogen Oxide Emissions by Mode: 1991-2001

TABLE 74b Nitrogen Oxide Emissions by Mode: 1991-2001

(Thousands of short tons)

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  1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Highway gasoline 6,072 5,811 5,548 5,287 5,026 4,765 4,705 4,509 4,312 4,201 4,345
Highway diesel 3,377 3,495 3,614 3,732 3,850 3,968 4,087 4,111 4,035 4,192 3,904
Aircraft 70 71 72 73 73 74 83 91 100 88 81
Marine vessels 1,012 1,021 1,030 1,039 1,049 1,058 1,008 958 908 1,008 1,011
Railroad 962 979 996 1,014 1,031 1,048 1,061 1,073 1,085 1,001 999
Other nonroad 70 68 72 72 72 77 83 78 96 83 83

NOTES: Highway gasoline vehicles include: light-duty gas vehicles and motorcycles, light-duty gas trucks, and heavy duty gas vehicles. Highway diesel includes heavy-duty diesel vehicles, light-duty diesel trucks and vehicles. Marine vessels include: coal, diesel, residual oil, gasoline and other. Other includes: diesel and gasoline recreational vehicles, airport service, railway maintenance, and recreational marine service. This table does not include farm, construction, industrial, logging, light commercial, and lawn and garden equipment.

SOURCE: U.S. Environmental Protection Agency (EPA), Office of Air Quality Planning and Standards, "National Emissions Inventory, Air Pollutant Emission Trends," available at http://www.epa.gov/ttn/chief/trends/index.html, as of August 2002.