Figure 11,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Index of Key Air Pollutant Emissions from U.S. Transportation: 1970-99,,,,,,,,,,,,,,,,,,,,,,,,,,,,
"Index: 1970 = 1.0, 1990 = 1.0 for PM-2.5 and ammonia",,,,,,,,,,,,,,,,,,,,,,,,,,,,

year,CO,NOx,VOC,PM-10,PM-2.5,Lead,Ammonia,,,,,,,,,,,,,,,,,,,,,
1970,1.00,1.00,1.00,1.00,,1.00,,,,,,,,,,,,,,,,,,,,,,
1971,0.99,1.06,0.96,1.06,,1.12,,,,,,,,,,,,,,,,,,,,,,
1972,1.02,1.15,0.95,1.11,,1.21,,,,,,,,,,,,,,,,,,,,,,
1973,1.01,1.20,0.92,1.14,,1.05,,,,,,,,,,,,,,,,,,,,,,
1974,0.94,1.14,0.83,1.10,,0.94,,,,,,,,,,,,,,,,,,,,,,
1975,0.95,1.17,0.83,1.13,,0.75,,,,,,,,,,,,,,,,,,,,,,
1976,0.95,1.21,0.79,1.13,,0.81,,,,,,,,,,,,,,,,,,,,,,
1977,0.96,1.23,0.81,1.13,,0.76,,,,,,,,,,,,,,,,,,,,,,
1978,0.97,1.27,0.78,1.12,,0.63,,,,,,,,,,,,,,,,,,,,,,
1979,0.91,1.23,0.72,1.07,,0.55,,,,,,,,,,,,,,,,,,,,,,
1980,0.90,1.22,0.73,1.04,,0.36,,,,,,,,,,,,,,,,,,,,,,
1981,0.87,1.18,0.71,0.94,,0.25,
1982,0.88,1.16,0.72,0.91,,0.24,
1983,0.90,1.16,0.73,0.91,,0.19,
1984,0.90,1.16,0.73,0.95,,0.17,
1985,0.90,1.19,0.76,1.01,,0.10,
1986,0.84,1.10,0.69,0.94,,0.06,
1987,0.82,1.09,0.67,1.01,,0.02,
1988,0.82,1.16,0.68,1.05,,0.02,
1989,0.77,1.19,0.60,1.06,,0.01,
1990,0.69,1.16,0.55,1.05,1.00,0.01,1.00
1991,0.74,1.21,0.56,1.06,1.01,0.00,1.06
1992,0.72,1.23,0.53,1.06,1.00,0.00,1.10
1993,0.73,1.25,0.54,1.00,0.94,0.00,1.15
1994,0.74,1.28,0.55,0.99,0.92,0.00,1.23
1995,0.65,1.26,0.50,0.89,0.82,0.00,1.33
1996,0.66,1.40,0.49,1.01,0.96,0.00,1.23
1997,0.65,1.42,0.49,0.98,0.93,0.00,1.38
1998,0.64,1.41,0.49,0.95,0.89,0.00,1.35
1999,0.62,1.38,0.48,0.86,0.85,0.00,1.39
,,,,,,,
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: US EPA, Office of Air Quality Planning and Standards, National Air",,,,,,,
Pollutant Trends http://www.epa.gov/ttn/chief/trends/index.html as of September 2001.,,,,,,,