"Table 4-44: Estimated National Emissions of Particulate Matter (PM-2.5)a,R (Million short tons)",,,,,,,,,,,,,,,
,1990,1991,1992,1993,1994,1995,1996,1997,1998,1999,2000,2001,,,
Total all sources,7.56,7.32,7.20,7.15,7.54,6.93,6.73,6.26,6.26,6.81,8.18,7.38,,,
"Transportation, total",2.67,2.69,2.64,2.71,2.71,2.50,2.30,2.40,2.38,2.02,2.31,2.35,,,
On-road vehicles,0.32,0.31,0.29,0.28,0.26,0.24,0.23,0.22,0.20,0.18,0.17,0.16,,,
Aircraft,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,<0.01,,,
Railroads,0.02,0.02,0.02,0.02,0.02,0.02,0.02,0.02,0.02,0.02,0.02,0.02,,,
Marine vessels,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,,,
Other off-roadb,0.03,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,0.04,,,
Transportation-related fugitive dust,,,,,,,,,,,,,,,
Unpaved roads,1.69,1.68,1.64,1.72,1.71,1.56,1.37,1.43,1.41,1.10,1.32,1.36,,,
Paved roads,0.56,0.60,0.61,0.62,0.63,0.58,0.60,0.65,0.67,0.63,0.71,0.72,,,
"Nontransportation, total",4.89,4.63,4.56,4.44,4.83,4.43,4.42,3.86,3.88,4.79,5.87,5.03,,,
Fuel combustion,0.91,0.89,0.93,0.85,0.84,0.90,0.67,0.67,0.63,0.96,1.34,1.32,,,
Industrial processesc,0.56,0.57,0.58,0.50,0.50,0.50,0.37,0.38,0.39,0.49,0.50,0.52,,,
Waste disposal and recycling,0.23,0.24,0.24,0.29,0.27,0.25,0.43,0.44,0.46,0.45,0.47,0.48,,,
Miscellaneousd,3.19,2.92,2.81,2.80,3.22,2.79,2.96,2.37,2.41,2.90,3.55,2.71,,,,
KEY:  R = revised.,,,,,,,,,,,,,,,,
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a Particulate matter less than 2.5 microns in size.,,,,,,,,,,,,,,,,
"b  Other off-road comprises nonroad gasoline- and diesel-powered recreational, airport service and railway maintenance vehicles, and recreational marine vessels.",,,,,,,,,,,,,,,,
"c  Industrial processes comprises chemical and allied product manufacturing, metals processing, petroleum and related industries, and other industrial processes; solvent utilization; and storage and transportation.",,,,,,,,,,,,,,,,
"d  Miscellaneous comprises nonroad gasoline- and diesel-powered construction, industrial, lawn and garden, farm, light-commercial, logging vehicles and other non-road sources; geogenic sources, agriculture and forestry, cooling towers, nontransportation-related fugitive dust, wildfires, managed burning, and other fugitive dust and combustion that could not accurately be allocated to specific source categories.",,,,,,,,,,,,,,,,
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NOTES ,,,,,,,,,,,,,,,,
"The emissions estimates shown here are those that are directly emitted, which represent only a portion of the total PM-2.5 emissions found in the air.  Secondary formation of fine particulates resulting from emissions of nitrogen oxide, sulfur dioxide, volatile organic compounds, and other substances, is also a significant source of PM-2.5.",,,,,,,,,,,,,,,,
Numbers may not add to totals due to rounding.,,,,,,,,,,,,,,,,
"The methodologies used to estimate emissions constantly evolve and undergo major changes.  These improved methods are often used to revise estimates for previous years and, therefore, some estimates in this table may not match estimates produced in previous reports.  The most recent revision of these estimates is based on Version 2 of the 1999 National Emissions Inventory (NEI) and provides a generally consistent time trend of the estimates.  However, state-submitted data on mobile sources is only reflected in the estimates for 1999 and the EPA plans to correct this inconsistency in future publications. ",,,,,,,,,,,,,,,,
"Except for residential wood combustion, included in the fuel combustion category, combustion source emissions for 1999-2001 include both the condensible and filterable PM fractions.  Emissions prior to 1999 include only the filterable PM fraction.  Residential wood combustion emissions include both the condensible and filterable PM fractions for all years.",,,,,,,,,,,,,,,,
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SOURCE,,,,,,,,,,,,,,,,
"
1990-2001: U.S. Environmental Protection Agency, Clearinghouse for Inventories and Emissions Factors (CHIEF), Current Emission Trends Summaries, available at Internet website http://www.epa.gov/ttn/chief/trends/ as of Aug. 14, 2003.  ",,,,,,,,,,,,,,,,
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