Regional Differences in Ozone
Region 7: Nebraska, Kansas, Iowa, and Missouri
Local Sources of VOCs
Human activity generated 979,660 tons of VOCs in Region 7 in 1999, the third lowest amount of 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.
Trends
This is the one region of the nation where monitored ozone levels remained unchanged between 1982 and 2001, in contrast to the nation as a whole, which dropped 11 percent during the same period. Furthermore, the region’s ozone levels rose by 13 percent from 1990-1999, the worst increase in any region during that decade.
|
