Table 4-44 :  Estimated National Emissions of Particulate Matter (PM-2.5)a (Million short tons),,,,,,,,,,
,1990,1991,1992,1993,1994,1995,1996,1997,1998,1999
TOTAL all sources,7.96,7.74,7.65,7.33,7.98,7.18,R7.70,R8.06,R7.86,N
Transportation,,,,,,,,,,
On-road vehicles,R0.29,0.29,0.28,0.26,0.26,R0.24,R0.28,R0.26,R0.25,0.23
Aircraft,0.03,0.03,0.03,0.03,0.03,0.03,0.03,0.03,0.03,0.03
Railroads,0.05,0.05,0.05,0.05,0.05,0.03,R0.03,0.03,0.03,0.03
Marine vessels,0.03,0.03,0.03,0.03,0.03,0.03,0.04,0.04,0.04,0.04
Other off-roadb,0.03,0.03,0.03,0.04,0.04,0.04,0.04,0.04,0.04,0.04
Transportation-related fugitive dust,,,,,,,,,,
  Unpaved roads,1.69,1.68,1.64,1.72,1.71,1.56,R1.37,R1.43,R1.41,1.41
  Paved roads,0.56,0.60,0.61,0.62,0.63,0.59,0.60,R0.65,R0.67,0.68
    Total transportation,R2.68,2.71,2.67,2.75,2.75,R2.50,R2.38,R2.48,R2.46,2.46
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Nontransportation,,,,,,,,,,
Fuel combustion,0.91,0.89,0.93,0.85,0.84,0.90,R0.85,R0.78,R0.74,0.77
Industrial processesc,0.56,0.57,0.58,0.50,0.50,0.50,R0.37,R0.38,0.39,0.39,,,,,,
Waste disposal and recycling,0.23,0.24,0.24,0.29,0.27,0.25,0.23,0.24,0.24,0.53,,,,,,
Miscellaneousd,3.59,3.32,3.22,2.95,3.62,3.04,R3.87,R4.19,R4.05,e2.63,,,,,,
    Total nontransportation,5.29,5.02,4.97,4.59,5.23,4.69,R5.33,R5.59,R5.41,N,,,,,,
KEY: N = data do not exist; 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 comprise 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).",,,,,,,,,,,,,,,,
e Miscellaneous data for 1999 does not include emissions from geogenic sources because the data was not estimated in 1999.  The methodologies used for obtaining geogenic emission data are still being improved and current estimates will be revised at a later date.,,,,,,,,,,,,,,,,
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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.  Improved methods are often used to revise estimates for previous years.  Therefore, some estimates in this table may not match estimates produced in previous reports, and some trends may not be consistent across years in which major changes in methodology have occurred.",,,,,,,,,,,,,,,,
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"SOURCES: 1990-99: U.S. Environmental Protection Agency, National Air Quality and Emissions Trends Report: 1999 (EPA-454/R-01-004) (Research Triangle Park, NC: March 2001), table A-9; available at Internet website http://www.epa.gov/oar/aqtrnd99/toc.html, as of Sept. 5, 2001. ",,,,,,,,,,,,,,,,
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