Table 5-11. Estimated National Average Vehicle Emissions Rates of Heavy-Duty and Light-Duty Vehicles: 1990-2005 (Grams Per Mile)

Air quality is affected by emissions from freight vehicles. Compared with gasoline- fueled cars and trucks, diesel-fueled heavy trucks emit small amounts of carbon monoxide (CO) but large amounts of nitrogen oxides (NOx).

Table in Excel format | Historical data

	1990	2000	2005	2006
Gasoline (assuming zero RFG)
Cars
Exhaust HC	2.79	0.97	0.52	0.46
Nonexhaust HC	1.21	0.92	0.72	0.68
Total HC	3.99	1.89	1.25	1.13
Exhaust CO	42.89	18.53	12.57	10.87
Exhaust NOx	2.70	1.29	0.92	0.79
Light trucks
Exhaust HC	3.68	1.45	0.78	0.69
Nonexhaust HC	1.36	0.97	0.76	0.71
Total HC	5.04	2.42	1.54	1.40
Exhaust CO	56.23	26.81	16.23	14.33
Exhaust NOx	2.62	1.54	1.21	1.09
Heavy trucks
Exhaust HC	3.66	1.22	0.64	0.53
Nonexhaust HC	2.74	1.62	1.24	1.14
Total HC	6.40	2.84	1.88	1.67
Exhaust CO	85.61	31.08	16.73	14.51
Exhaust NOx	7.19	5.26	4.28	3.73
Diesel
Cars
Exhaust HC	0.68	0.80	0.58	0.48
Exhaust CO	1.49	1.78	1.57	1.41
Exhaust NOx	1.83	1.81	1.32	1.11
Light trucks
Exhaust HC	1.59	1.02	0.80	0.79
Exhaust CO	2.67	1.77	1.37	1.34
Exhaust NOx	2.71	1.76	1.37	1.30
Heavy trucks
Exhaust HC	2.21	0.79	0.54	0.51
Exhaust CO	10.06	4.10	3.05	2.90
Exhaust NOx	23.34	18.05	11.45	10.55

Key: CO = carbon monoxide; HC = hydrocarbon; NO_x = nitrogen oxides; RFG = reformulated gasoline.

Source: U.S. Environmental Protection Agency, National Vehicle and Fuel Emissions Laboratory, personal communication, August 8, 2007.

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