Transportation energy data book: edition 23 - Oak Ridge National ...

The transportation sector accounted for over half of the nation’s nitrogen oxide (NOx) emissions in
2001, with the majority coming from highway vehicles. For details on the highway emissions of NOx,
see Table 12.5.
Table 12.4
Total National Emissions of Nitrogen Oxides, 1980–2001 a
(million short tons)
Source category 1980 1985 1990 1995 2000 2001
Highway vehicles
Railroads
Other off-highway
11.49
1.19
2.17
10.93
0.96
2.62
9.59
0.95
2.84
a The sums of subcategories may not equal total due to rounding.
8.88
1.03
3.08
TRANSPORTATION ENERGY DATA BOOK: EDITION 23—2003
8.39
1.00
3.17
8.25
1.00
3.16
Percent
of total,
2001
36.9%
4.5%
14.1%
Transportation total 14.85 14.51 13.38 12.99 12.56 12.41 55.5%
Stationary fuel combustion total 11.32 10.05 10.89 10.83 9.04 8.60 38.5%
Industrial processes total 0.56 0.80 0.80 0.77 0.83 0.86 3.9%
Waste disposal and recycling total 0.11 0.09 0.09 0.10 0.17 0.17 0.8%
Miscellaneous total 0.25 0.31 0.37 0.27 0.61 0.31 1.4%
Total of all sources 27.08 25.76 25.53 24.96 23.20 22.35 100.0%
Source:
U. S. Environmental Protection Agency, National Emission Inventory Air Pollutant Emission Trends
website www.epa.gov/ttn/chief/trends (Additional resources: www.epa.gov/oar/oaqps)
12–5