Figure 9 - Index of Key Air Pollutant Emissions from U.S. Transportation: 1970-98

Figure 9
Index of Key Air Pollutant Emissions from U.S. Transportation: 1970-98
Index: 1970 = 1.0, 1990 = 1.0 for PM-2.5

Figure 9, Index of Key Air Pollutant Emissions from U.S. Transportation: 1970-98

Key: NOx = oxides of nitrogen; PM-10 and PM-2.5 = airborne particulates of less than 10 microns or 2.5 microns, respectively; CO = carbon monoxide; VOC = volatile organic compounds.

Note: Transportation emissions include all onroad mobile sources and the following nonroad mobile sources: recreational vehicles and boats, airport service equipment, aircraft, commercial marine vessels, and railroads. Other nonroad sources, such as lawnmowers and farming equipment, are not included. Lead estimates include onroad mobile sources only.

Source: U.S. Environmental Protection Agency, Office of Air and Radiation, Air Quality Planning and Standards, National Air Quality and Emission Trends, 1900-1998, available at www.epa.gov/ttn/chief/trends98/emtrnd/html, as of December 2000.