NOx Emissions from Highway Vehicles, 1970-2005* (million short tons)
Heavy diesel-powered vehicles were responsible for nearly one-half (44.1%) of highway vehicle
nitrogen oxide emissions in 2005, while light gasoline vehicles were responsible for the rest.
| Source category | 1970 | 1980 | 1990 | 1995 | 2000 | 2005 | Percent of total, 2005 |
|---|---|---|---|---|---|---|---|
| gasoline powered | |||||||
Light vehicles |
8.54 |
6.63 |
4.26 |
3.05 |
2.31 |
1.63 |
25.5% |
Light trucks + |
1.54 |
1.58 |
1.50 |
1.46 |
1.44 |
1.56 |
24.4% |
Heavy vehicles |
0.72 |
0.62 |
0.57 |
0.52 |
0.45 |
0.38 |
5.9% |
Total |
10.81 |
8.83 |
6.33 |
5.03 |
4.20 |
3.57 |
55.9% |
| diesel powered | |||||||
Light vehicles |
0.00 |
0.03 |
0.04 |
0.02 |
0.01 |
0.00 |
0.0% |
Light trucks + |
0.07 |
0.05 |
0.02 |
0.01 |
0.01 |
0.01 |
0.2% |
Heavy vehicles |
1.76 |
2.59 |
3.19 |
3.82 |
4.18 |
2.81 |
44.0% |
Total |
1.83 |
2.66 |
3.26 |
3.85 |
4.19 |
2.82 |
44.1% |
| total | |||||||
Highway vehicle |
12.64 |
11.49 | 9.59 |
8.88 |
8.39 |
6.39 |
100.0% |
| Percent diesel | 14.5% | 23.1% | 34.0% | 43.4% | 49.9% | 44.1% | -- |
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)
* The sums of subcategories may not equal total due to rounding.
+ Less than 8,500 pounds.
