Figure 14 Index of Key Air Pollutant Emissions from U.S. Transportation: 1990-2003

Figure 14 Index of Key Air Pollutant Emissions from U.S. Transportation: 1990-2003

Index: 1990 = 1.0

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Year CO NOx VOC PM-10 PM-2.5 Lead SO2
1990 1.00 1.00 1.00 1.00 1.00 1.00 1.00
1991 0.95 0.99 0.94 0.96 0.95 0.04 0.93
1992 0.90 0.97 0.89 0.91 0.90 0.04 0.87
1993 0.86 0.96 0.83 0.87 0.85 0.04 0.80
1994 0.81 0.94 0.78 0.83 0.81 0.05 0.73
1995 0.76 0.93 0.72 0.79 0.76 0.05 0.67
1996 0.71 0.91 0.66 0.74 0.71 0.05 0.60
1997 0.69 0.92 0.64 0.71 0.67 0.05 0.60
1998 0.66 0.90 0.62 0.66 0.62 0.05 0.60
1999 0.62 0.87 0.61 0.62 0.57 0.00 0.60
2000 0.62 0.88 0.57 0.59 0.54 0.00 0.52
2001 0.58 0.81 0.53 0.55 0.49 0.00 0.49
2002 0.56 0.77 0.48 0.53 0.46 0.00 0.55
2003 0.53 0.77 0.47 0.48 0.41 0.00 0.51

Key: PM-10 and PM-2.5 = airborne particulates of less than 10 microns or 2.5 microns, respectively.

Notes: Data in the previous edition include all onroad mobile sources and some nonroad mobile sources. EPA revised the emissions estimation methodology for onroad mobile sources. EPA discontinued lead emissions estimated in 2001.

Source: U.S. Environmental Protection Agency (EPA), Office of Air Quality Planning and Standards, Air Emissions Trend, available at http://www.epa.gov/airtrends/2005/econ-emissions.html, as of December 2005.