Table 4-38: Estimated National Average Vehicle Emissions Rates by Vehicle Type and Fuel

Table 4-38: Estimated National Average Vehicle Emissions Rates by Vehicle Type and Fuel

(Grams per mile)

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  1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 E2001
GASOLINE (assuming zero RFG)                        
Light-duty vehicles                        
Exhaust HC 2.05 1.92 1.81 1.72 1.66 1.60 1.55 1.51 1.47 1.44 1.42 1.41
Nonexhaust HC 1.04 0.99 0.96 0.93 0.91 0.89 0.87 0.85 0.82 0.79 0.74 0.69
Total HC 3.09 2.91 2.77 2.65 2.57 2.49 2.42 2.36 2.29 2.23 2.16 2.10
Exhaust CO 24.68 23.42 22.40 21.65 21.10 20.52 20.14 19.86 19.52 19.36 19.28 19.23
Exhaust NOx 1.81 1.76 1.72 1.69 1.67 1.61 1.56 1.51 1.45 1.41 1.38 1.35
Light-duty trucks                        
Exhaust HC 3.24 3.03 2.80 2.61 2.46 2.31 2.21 2.13 2.05 1.99 1.95 1.92
Nonexhaust HC 1.44 1.31 1.21 1.16 1.11 1.07 1.03 1.01 0.96 0.94 0.90 0.87
Total HC 4.68 4.34 4.01 3.77 3.57 3.38 3.24 3.14 3.01 2.93 2.85 2.79
Exhaust CO 36.32 34.01 31.78 30.03 28.62 27.41 26.83 26.38 25.69 25.29 24.99 24.79
Exhaust NOx 2.36 2.25 2.16 2.10 2.04 1.97 1.95 1.92 1.87 1.84 1.80 1.77
Heavy-duty vehicles                        
Exhaust HC 7.45 6.79 6.22 5.53 4.92 4.51 4.13 3.73 3.33 3.07 2.82 2.63
Nonexhaust HC 4.44 4.11 3.84 3.71 3.57 3.38 3.17 2.97 2.78 2.63 2.50 2.37
Total HC 11.89 10.90 10.06 9.24 8.49 7.89 7.30 6.70 6.11 5.70 5.32 5.00
Exhaust CO 131.19 120.49 111.05 101.92 93.61 85.10 76.97 69.13 61.07 54.65 48.67 43.65
Exhaust NOx 6.49 6.28 6.05 5.85 5.69 5.48 5.36 5.25 5.05 4.89 4.72 4.56
Motorcycles                        
Exhaust HC 2.31 2.19 2.11 2.05 2.02 1.96 1.93 1.92 1.90 1.89 1.89 1.89
Nonexhaust HC 2.37 2.37 2.37 2.36 2.36 2.37 2.36 2.37 2.37 2.37 2.37 2.37
Total HC 4.68 4.56 4.48 4.41 4.38 4.33 4.29 4.29 4.27 4.26 4.26 4.26
Exhaust CO 20.89 20.61 20.60 20.59 20.59 20.47 20.47 20.47 20.35 20.35 20.35 20.35
Exhaust NOx 0.85 0.85 0.85 0.85 0.85 0.84 0.84 0.84 0.83 0.83 0.83 0.83
DIESEL                        
Light-duty vehicles                        
Exhaust HC 0.73 0.74 0.75 0.75 0.76 0.77 0.76 0.74 0.71 0.67 0.63 0.59
Exhaust CO 1.68 1.71 1.72 1.73 1.74 1.74 1.74 1.71 1.67 1.62 1.57 1.53
Exhaust NOx 1.65 1.67 1.68 1.68 1.66 1.64 1.60 1.55 1.48 1.40 1.33 1.26
Light-duty trucks                        
Exhaust HC 1.08 1.14 1.15 1.14 1.13 1.11 1.09 1.05 0.98 0.91 0.84 0.78
Exhaust CO 2.03 2.10 2.09 2.07 2.04 2.02 1.99 1.95 1.88 1.80 1.73 1.68
Exhaust NOx 1.97 2.00 1.99 1.97 1.94 1.90 1.85 1.78 1.67 1.56 1.46 1.38
Heavy-duty vehicles                        
Exhaust HC 3.30 3.08 2.89 2.75 2.65 2.54 2.44 2.36 2.30 2.25 2.22 2.19
Exhaust CO 13.71 13.38 13.07 12.76 12.50 12.28 12.08 11.93 11.77 11.63 11.53 11.45
Exhaust NOx 21.05 19.59 18.14 16.89 15.81 14.79 13.96 13.33 12.66 11.93 11.24 10.59
AVERAGE OF ALL VEHICLES, GASOLINE AND DIESEL                        
Exhaust HC 2.56 2.40 2.25 2.13 2.03 1.93 1.86 1.80 1.74 1.70 1.67 1.64
Nonexhaust HC 1.18 1.12 1.06 1.02 1.00 0.97 0.94 0.91 0.88 0.84 0.80 0.76
Total HC 3.75 3.52 3.31 3.15 3.02 2.90 2.80 2.71 2.62 2.54 2.47 2.40
Exhaust CO 29.97 28.29 26.81 25.62 24.68 23.75 23.11 22.58 21.94 21.53 21.20 20.95
Exhaust NOx 3.09 2.99 2.89 2.80 2.73 2.63 2.56 2.50 2.41 2.34 2.27 2.21

KEY: CO = carbon monoxide; E = estimate; HC = hydrocarbon; NOx = nitrogen oxide; R = revised; RFG = reformulated gasoline.

NOTES: As of July 1 of each year. Vehicles types are defined as follows: light-duty vehicles (passenger cars up to 6,000 lb GVWR); light-duty trucks (pickups and minivans up to 8,500 lb GVWR); heavy-duty vehicles (8,501 lbs or more GVWR); motorcycle (highway only). This table is based on MOBILE5b, the U.S. Environmental Protection Agency's (EPA) latest highway vehicle emissions factor model. Interested readers can learn more about the Mobile5b model at the following USEPA Internet site http://www.epa.gov/otaq.

MOBILE5b is undergoing a major revision and is expected to be replaced by MOBILE6 in early 2002. Emissions factors are national averages based on the following assumptions: ambient temperature 75 F, daily temperature range 60-84 F, average traffic speed 19.6 mph (representative of overall traffic in urban areas), standard operating mode (cold-start, hot-start, stabilized), vehicle-miles traveled fractions, no inspection/maintenance or antitampering programs, and gasoline volatility 9.0 per square inch RVP (Reid vapor pressure).

See Table 4-39 for emissions from vehicles operating on reformulated gasoline.

Data for nonexhaust HC is negligible for diesel light-duty vehicles, light-duty trucks, and heavy-duty vehicles.

SOURCE: U.S. Environmental Protection Agency, National Vehicle and Fuel Emissions Laboratory, personal communication, Sept. 13, 2001.