TABLE 74a Change in Nitrogen Oxide Emissions by Mode: 1991-2001

TABLE 74a Change in Nitrogen Oxide Emissions by Mode: 1991-2001

Index: 1991 = 1.00

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  1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001
Highway gasoline 1.00 0.96 0.91 0.87 0.83 0.78 0.77 0.74 0.71 0.69 0.72
Highway diesel 1.00 1.03 1.07 1.11 1.14 1.18 1.21 1.22 1.19 1.24 1.16
Aircraft 1.00 1.01 1.03 1.04 1.04 1.06 1.19 1.30 1.43 1.26 1.16
Marine vessels 1.00 1.01 1.02 1.03 1.04 1.05 1.00 0.95 0.90 1.00 1.00
Railroad 1.00 1.02 1.04 1.05 1.07 1.09 1.10 1.12 1.13 1.04 1.04
Other nonroad 1.00 0.97 1.03 1.03 1.03 1.10 1.19 1.11 1.37 1.19 1.19

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. These tables do 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.