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The mountains of East Tennessee are getting back to being more smoky and less smoggy because the Tennessee Valley Authority has spent a combined $5.3 billion since the 1970s curtailing air pollutants created at its 11 coal-burning power plants, TVA officials say.
Two big ozone-producing culprits -- sulfur dioxide and nitrogen oxide -- have been reduced by more than 90 percent from peak levels. And with more planned coal plant closures -- and another $2.2 billion slated for emission control -- those levels are expected to continue to decline, said Duncan Mansfield, a spokesman for TVA.
By 2017, nearly 30 units at its coal-burning power plants will be closed, converted or cleaned up with emission-reducing "scrubbers" as part of an agreement with the Environment Protection Agency, Mansfield said.
That's good news to Jim Renfro, air quality specialist for the national park. His office has been studying ozone in the Smokies from the Look Rock monitoring station for 30 years.
The blue haze that forms naturally around the Smokies is returning, and the thick white funk that wafts in from urban areas is thinning out, he said.
"It's getting back to its natural state. It used to be, this time of year, the mountains would be gone in the haze. Now that's the exception," Renfro said.
Visibility from the 2,700-foot elevation observation tower at Look Rock was 40 miles Thursday. In a perfect world, it would be 70 miles, Renfro said.
But despite the vast improvements, the park is still in ozone nonattainment.
It needs 76 parts per billion of ozone or less, but it has 77.
"But in 1999, we were at 104 ppb for a three-year average. Basically, ozone has decreased 26 percent," Renfro said.
For perspective: After great improvements, the Smokies have the same borderline ozone attainment score as Hamilton County. But Hamilton County has official ozone attainment as part of an emissions agreement with EPA, according to Bob Colby, director of the Chattanooga/Hamilton County Air Pollution Control Bureau.
THE RESEARCH OPPORTUNITY
Look Rock is one of the only ridgetop air quality monitoring sites on the East Coast, and the Smoky Mountains are "an environmental barometer for the whole region," Mansfield said.
Its location, along with the unique, trackable changes in ozone and the 30-year record of historical data, made Look Rock a perfect fit for a $20 million research campaign aimed at divining how natural emissions mingle with man-made ones to create ozone.
The project is called the Southern Oxidant and Aerosol Study, and it's funded by the EPA, National Science Foundation and the National Oceanic and Atmospheric Administration, with TVA, Southern Co. and the Electric Power Research Institute contributing.
Sherri Hunt, a scientist with the EPA's office of research and development, said the work eventually could guide air pollution policy in the region.
"Two big goals are really understanding the way emissions from natural sources are compounded by man-made emissions," Hunt said. "We want to know how they form this haze. ... Our models don't really get it right."
Hunt said the Look Rock station is important for researching emission controls, ozone and other air quality problems because it provides follow-up data for air masses leaving another research station in Centerville, Ala. That data improves models that forecast ozone changes.
Ultimately, the research can help policymakers craft better, more accurate air quality regulations.
"You'll have a better idea about what happens when you close a power plant or change rules for fuel emissions," Hunt said. "The model improvements that are made here will be applicable to Chattanooga and across the country."
One of the missing links in understanding atmospheric interaction is how isoprene, a chemical released by vegetation, mingles with other coal, fuel and other man-made emissions. Look Rock is the perfect place for studying isoprene chemistry, Hunt said.
Janin Guzman is a doctoral student at the University of California-San Diego who is working on the project along with five other students from UC-Davis and the University of North Carolina.
She said the team has collected an enormous amount of information about ozone and particulate matter. Once the team returns from the field, members will determine what the data mean.
"This is just the start of the investigation. We want to be here to study measurements. But once we get home, we have a lot of work to do," Guzman said.
Contact staff writer Louie Brogdon at firstname.lastname@example.org or 423-757-6481. Follow him on Twitter at @glbrogdoniv.