KEY: 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%. See table 10-1 in appendix B for definitions of “highway” and “other” vehicles.
SOURCE: U.S. Environmental Protection Agency, 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 August 2003.