Table 4-41: Estimated National Emissions of Nitrogen
Oxides
(Million short tons)
Excel | CSV
| 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.
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