As Colorado struggles to crack down on smog in Rocky Mountain National Park and the Front Range, a satellite study of the Ohio River Valley may offer lessons on curbing pollution.
The coal-burning power plants in the Ohio River Valley long have contributed to haze in the northeastern states, and in the 1990s, federal laws targeted emissions from those plants.
“The regulations are working,” said Si-Wan Kim, an atmospheric scientist at the National Oceanic and Atmospheric Administration in Boulder and the University of Colorado.
Kim and her colleagues used satellites to study oxides of nitrogen emitted by Ohio Valley plants and the effect of those emissions on ozone pollution in the northeast.
Nitrogen oxides combine with other chemicals in sunlight to form ozone haze, which can impair human health, natural ecosystems and visibility.
Between 1999 and 2005, there was a 38 percent drop in nitrogen oxide emissions in the Ohio River Valley, Kim said.
The researchers’ work, to be published in Wednesday’s issue of Geophysical Research Letters, is the first to demonstrate that satellite data can be used to look at regional nitrogen pollution trends, Kim said.
The team now plans to turn its attention west, Kim said.
Power plants and cities tend to be more isolated in the West than in the East.
As a result, scientists should be able to use satellites to study the contributions of individual coal-fired power plants – such as those in the Four Corners area, Craig and Hayden – to creating haze, Kim said.
Researchers should also be able to identify trends in nitrogen production in individual cities such as Denver, where more nitrogen pollution is more likely to come from tailpipes than power plant stacks.
Vickie Patton, an Boulder-based attorney for Environmental Defense, said more data should help policy makers figure out how to reduce the nitrogen pollution that stresses mountain ecosystems.
State health officials are working with power plants to cut nitrogen oxide emissions and control visibility-damaging smog.
Health officials recently decided, however, not to force power plants to use a control technology called selective catalytic reduction, Patton said.
“That was enormously frustrating, because it has proven so effective in lowering pollution elsewhere,” Patton said.
Selective catalytic reduction is one of several techniques adopted by Ohio Valley power plants to cut emissions between 1999 and today, Kim said.
Ethnie Groves, spokeswoman for Xcel Energy Inc., said that although power plants may contribute to ozone haze in Colorado’s Front Range or mountain parks, other sources such as cars and energy production are probably the main cause.
Still, the company has reduced nitrogen pollution from three Denver-area power plants by 40 percent between 1995 and 2003, she said.
Mike Silverstein, deputy director of Colorado’s air pollution control division, said power plants are among several sources of nitrogen pollution under review in the state’s smog-control effort.
Staff writer Katy Human can be reached at 303-954-1910 or khuman@denverpost.com.
This story has been clarified in this online archive. Originally it did not make clear Xcel Energy Inc.’s position on regional smog. A company official clarified that although power plants may contribute to regional smog, other sources, such as cars and energy production, are probably the main cause.
