Table 4-45:  Estimated National Emissions of Sulfur Dioxide (Million short tons),,,,,,,,,,,,,,,,,,,,,
,1970 ,1975 ,1980,1985,1990 ,1991,1992,1993,1994,1995 ,1996 ,1997 ,1998 ,1999,,,,,,,
Transportation,,,,,,,,,,,,,,,,,,,,,
On-road vehicles,0.41,0.50,0.52,0.52,R0.56,0.57,0.59,0.53,0.31,R0.31,R0.34,R0.35,R0.36,0.36,,,,,,,
Off-road,,,,,,,,,,,,,,,,,,,,,
  Aircraft,<0.01,<0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,0.01,,,,,,,
  Railroads,0.04,0.04,0.05,0.06,0.12,0.12,0.13,0.12,0.11,0.11,0.11,0.12,0.11,0.11,,,,,,,
  Marine vessels,0.04,0.05,0.12,0.14,0.25,0.26,0.26,0.25,0.25,0.24,0.24,0.25,0.26,0.27,,,,,,,
    Total transportation,0.49,0.59,0.70,0.73,R0.94,0.96,0.98,0.90,0.68,R0.67,R0.70,R0.72,R0.74,0.76,,,,,,,
,,,,,,,,,,,,,,,,,,,,,
Nontransportation,,,,,,,,,,,,,,,,,,,,,
Fuel combustion,23.46,22.66,21.39,20.02,20.29,19.80,19.49,19.25,18.89,16.23,R16.23,R16.65,R16.75,16.36,,,,,,,
Industrial processesa,7.09,4.68,3.77,2.43,1.86,1.68,1.72,1.65,1.62,1.59,R1.38,R1.43,R1.43,1.43,,,,,,,
Waste disposal and recycling,0.01,0.05,0.03,0.03,0.04,0.04,0.04,0.07,0.06,0.05,0.04,0.04,0.04,0.04,,,,,,,
Miscellaneousb,0.11,0.02,0.01,0.44,0.55,0.56,0.58,0.61,0.63,0.65,R0.51,R0.52,R0.53,0.55,,,,,,,
    Total nontransportation,30.67,27.41,25.20,22.92,22.74,22.08,21.83,21.57,21.19,18.52,R18.16,R18.64,R18.75,18.38,,,,,,,
,,,,,,,,,,,,,,,,,,,,,
TOTAL all sources,31.16,28.01,25.91,23.66,R23.68,23.04,22.81,22.48,21.88,R19.19,R18.86,R19.36,R19.49,19.14,,,,,,,
KEY:  R = revised.,,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,
"a Industrial processes comprise chemical and allied product manufacturing, metals processing, petroleum and related industries, and other industrial processes; solvent utilization; and storage and transport. ",,,,,,,,,,,,,,,,,,,,,
"b Miscellaneous comprises nontransportation-related fugitive dust, nonroad gasoline, nonroad diesel, other nonroad sources and other miscellaneous combustion that could not be accurately allocated to specific source categories. ",,,,,,,,,,,,,,,,,,,,,
,,,,,,,,,,,,,,,,,,,,,
"NOTES: The methodologies used to estimate emissions constantly evolve and undergo major changes.  These 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 methodology changes have occurred. ",,,,,,,,,,,,,,,,,,,,,
Numbers may not add to totals due to rounding.,,,,,,,,,,,,,,,,,,,,,
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"SOURCES:  1970-85, 1989-99: 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-8; available at Internet website http://www.epa.gov/oar/aqtrnd99/toc.html, as of Sep. 5, 2001. ",,,,,,,,,,,,,,,,,,,,,
"1988: Ibid, National Air Pollutant Emission Trends: 1900-1998 (EPA-454/R-00-002) (Research Triangle Park, NC: March 2000), table A-4; available at Internet website http://www.epa.gov/ttn/chief/trends/trends98/browse.html, as of Sep. 5, 2001. ",,,,,,,,,,,,,,,,,,,,,
"1986-87: Ibid, National Emission Trends source reports database, available at Internet website www.epa.gov/air/data/nettier.html, as of Sep. 5, 2001.",,,,,,,,,,,,,,,,,,,,,