Table 4-41: Estimated National Emissions of Nitrogen Oxides

Table 4-41: Estimated National Emissions of Nitrogen Oxides

(Million short tons)

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  1970 1975 1980 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
TOTAL all sources 26.88 26.38 27.08 25.76 25.42 25.58 26.07 25.38 25.53 25.18 25.26 25.36 25.35 24.96 24.79 24.71 24.35 (R) 22.85 (R) 22.60 (R) 21.55 21.10
Transportation, total 14.83 14.26 13.74 13.06 12.92 12.79 12.42 12.05 11.68 11.56 11.45 11.33 11.22 11.10 10.99 11.02 10.82 (R) 10.36 10.57 (R) 9.95 9.44
On-road vehicles 12.62 12.06 11.49 10.93 10.82 10.71 10.34 9.96 9.59 9.45 9.31 9.16 9.02 8.88 8.73 8.79 8.62 (R) 8.37 8.39 (R) 7.77 7.37
Off-road, total 2.20 2.20 2.25 2.13 2.10 2.08 2.08 2.08 2.08 2.11 2.14 2.17 2.20 2.23 2.26 2.23 2.20 (R) 1.99 2.18 (R) 2.18 2.07
Aircraft 0.05 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.07 0.08 0.09 0.10 0.09 0.08 0.08
Railroads 1.14 1.11 1.19 0.96 0.91 0.87 0.89 0.92 0.95 0.96 0.98 1.00 1.01 1.03 1.05 1.06 1.07 (R) 0.94 1.00 1.00 0.89
Marine vessels 0.98 0.99 0.95 1.04 1.06 1.08 1.05 1.03 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.01 0.96 (R) 0.86 1.01 1.01 1.01
Other off-roada 0.04 0.05 0.05 0.06 0.06 0.06 0.06 0.06 0.07 0.07 0.07 0.07 0.07 0.07 0.08 0.08 0.08 0.10 0.08 0.08 0.09
Nontransportation, total 12.06 12.12 13.34 12.70 12.50 12.80 13.66 13.33 13.85 13.62 13.82 14.03 14.13 13.85 13.80 13.68 13.53 (R) 12.49 (R) 12.03 (R) 11.60 11.67
Fuel combustion 10.06 10.49 11.32 10.05 9.87 10.01 10.47 10.54 10.89 10.78 10.93 11.11 11.02 10.83 10.51 10.55 10.38 (R) 9.20 (R) 8.82 (R) 8.45 8.29
Industrial processesb 0.78 0.54 0.56 0.80 0.79 0.76 0.78 0.77 0.80 0.72 0.76 0.74 0.77 0.77 0.80 0.84 0.85 (R) 0.78 (R) 0.81 (R) 0.85 0.85
Waste disposal and recycling 0.44 0.16 0.11 0.09 0.09 0.09 0.09 0.08 0.09 0.10 0.10 0.12 0.11 0.10 0.15 0.16 0.16 (R) 0.16 (R) 0.13 (R) 0.13 0.15
Miscellaneousc 0.78 0.94 1.35 1.76 1.76 1.94 2.33 1.94 2.07 2.03 2.03 2.05 2.24 2.15 2.33 2.13 2.14 (R) 2.35 (R) 2.26 (R) 2.17 2.37

KEY: R = revised.

a Other off-road comprises nonroad gasoline- and diesel-powered recreational, airport service and railway maintenance vehicles, and recreational marine vessels.

b Industrial processes comprises chemical and allied product manufacturing, metals processing, petroleum and related industries, and other industrial processes; and solvent utilization, storage, and transport.

c Miscellaneous comprises nonroad gasoline- and diesel-powered construction, industrial, lawn and garden, farm, light-commercial, logging vehicles, and other nonroad sources; agriculture and forestry, health services, cooling towers, fugitive dust; and other combustion sources that could not be accurately allocated to specific source categories.

NOTES

The methodologies used to estimate emissions constantly evolve and undergo major changes. These improved methods are often used to revise estimates for previous years and, therefore, some estimates in this table may not match estimates produced in previous reports.

Numbers may not add to totals due to rounding.

SOURCE

1970-2002: U.S. Environmental Protection Agency, Clearinghouse for Inventories and Emissions Factors (CHIEF), Current Emission Trends Summaries, Internet website http://www.epa.gov/ttn/chief/trends/ as of Dec. 20, 2004.