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Regional Differences on Sources for Ozone and Particle Pollution
Region 7: Iowa, Kansas, Missouri and Nebraska
Local Sources of VOCs
Human activity generated 979,660 tons of VOCs in Region 7 in 1999, the third lowest amount in any region. It is unusual that the largest sources are solvents at 33 percent, higher than the national rate of 27 percent, which may reflect the greater rural nature of large parts of the region. Highway vehicles generate the second highest amount of VOCs, which at 29 percent is the same as the nationwide rate. Off-highway vehicles generate 12 percent of VOCs regionally, which is one-third lower than the national rate of 18 percent. VOCs from chemical and allied industries are also three times higher in this region than nationally (6% v 2%).
Local Sources of NOx
Highway vehicles, at 30 percent, are the largest source of NOx emissions in this region — but they account for less in Region 7 than nationally (33%). NOx from off-highway vehicles is significantly higher here than nationwide (28% v 22%). Electric utilities produce about one-fourth of NOx here, about the same as nationwide (24% v 23%). Industrial fuel combustion is about the same, though other fuel combustion is less than half the percentage nationwide. Total NOx in 1999 in Region 7 was 1.6 million tons.
Local sources of Particle Pollution (PM 2.5)
Agriculture and forestry, and other combustion were the major sources of particle pollution in Region 7 (69%); well above the national average of 47 percent for miscellaneous sources of particle pollution. Off-highway vehicles are the second largest source of particle pollution emissions at 7 percent. Other fuel combustion was the third largest source of particle pollution emissions at 6 percent, waste disposal and recycling followed at 5 percent. Region 7 measured 388,757 short tons of particle pollution during the 1999 inventory.
Trends
Monitored ozone levels dropped by 4 percent between 1983 and 2002, far behind the nation as a whole, which dropped 14 percent during the same period. Furthermore, the long-term decline could have been greater had not the region’s ozone levels gone up by 2.7 percent from 1991-2000, the 3rd worst increase in any region during that decade. Comparable trend data are not available for PM2.5 levels.
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