KEY: CO = carbon monoxide; NOx = nitrogen oxides; VOC = volatile organic compounds; PM-10 = particulate matter 10 microns in diameter or smaller.
NOTES: EPA no longer estimates lead emissions. Modal shares in 2000 were: highway gasoline vehicles, 4.1%; aircraft, 95.9%. Highway gasoline vehicles include: light-duty gas vehicles and motorcycles, light-duty gas trucks, and heavy-duty gas vehicles. Highway diesel includes heavy-duty diesel vehicles, light-duty diesel trucks and vehicles. Marine vessels include: coal, diesel, residual oil, gasoline and other. Other includes: diesel and gasoline recreational vehicles, airport service, railway maintenance, and recreational marine service. This table does not include farm, construction, industrial, logging, light commercial, and lawn and garden equipment.
SOURCE: U.S. Environmental Protection Agency (EPA), Office of Air Quality Planning and Standards, "National Emissions Inventory, Air Pollutant Emission Trends," available at http://www.epa.gov/ttn/chief/trends/index.html/, as of December 2002.