Figure 2 - Modal Share of Key Transportation Air Pollutants: 1999

Figure 2 - Modal Share of Key Transportation Air Pollutants: 1999

(Percent)

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  CO NOx VOC PM-10 Lead
Highway gasoline 85.63 43.82 74.95 23.1 4.1
Highway diesel 3.99 32.15 4.31 41.3 0
Aircraft 1.81 1.56 2.74 8.3 95.9
Marine Vessels 0.25 8.9 0.5 10.0 0
Railroad 0.21 10.65 0.73 6.55 0
Othera 8.11 2.92 16.77 10.69 0

aOther includes gasoline and diesel recreational vehicles, recreational marine vessels, airport service vehicles, and railroad maintenance equipment. Does not include farm, construction, industrial, logging, light commercial, and lawn and garden equipment.

KEY: CO = carbon monoxide; NOx = nitrogen oxides; VOC = volatile organic compounds; PM-10 = particulate matter 10 microns in diameter or smaller.

SOURCE: U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, "National Emission Inventory (NEI), Air Pollutant Emission Trends," available at http://www.epa.gov/ttn/chief/trends/, as of January 2001.