include industrial processes, power plants that are both coal and oil-fired, residential heating, and transportation. But coal burning is the greatest source. Table 1 below shows estimates of U.S. particulate emissions from various sources. TABLE 1 National U.S. Emissions Estimates-1990 (Million metric tons/year) SOURCE PARTICULATES SULFUR OXIDES CARBON MONOXIDES Transportation Highway 1.3 0.6 30.3 Aircraft 0.1 0 1.1 Rail&Sea 0 0.3 1.9 Off-Highway equipment 0.1 0.1 4.4 TOTAL 1.5 1 37.7 Stationary fuel combustion Electric utilities 0.4 14.2 0.3 Indusrial furnaces 0.3 2.3 0.7 Commercial 0 0.4 0.1 Residential 1 0.3 6.4 TOTAL 1.7 17.2 7.5 Industrial processes 2.8 3.1 4.7 Solid waste disposal 0.3 0 1.7 Miacellaneous Forest fires 1.1 0 8.1 Other burning 0.1 0 0.6 Misc. Organic solvents 0 0 0 TOTAL 1.2 0 8.7 OVERALL TOTAL 7.5 21.3 60.3 Only 13% of the total is generated by transportation. Industrial sources account for nearly three times as much as 37%. Fires account for just about as much particulate emissions as transportation. That amount is matched by combustion from sources, which include the generation of all heat and electricity. Emissions When coal was the main source to generate energy, power plants and homes accounted for much greater contribution. The switch to oil and nuclear power has lowered those concentrations, but it hasn't been without its own problems. In addition to health-related problems, particles can damage materials through corrosion and erosion, as well as soiling. Particles can also impact the weather, through changes in visibility, and even in enhancing precipitation. Studies around major urban areas show an increase in precipitation and in thunderstorms with hail downwind from downtown areas. The weather modification is localizes but definite, and may be related to an increase in the large condensation nuclei that the particles provide. Lead particulates are brutal primary pollutant. Their presence in the atmospher...
