LOS ANGELES -- The nation's air-quality picture improved overall from 1989 to 1998, but grew hazy in many national parks, according to a report released Wednesday by the U.S. Environmental Protection Agency.
The annual report found that ozone levels rose significantly in seven of 24 national parks measured, from the Great Smoky Mountains in North Carolina and Tennessee to Denali in Alaska.
The ozone news was better for Southern Californians, who breathe some of the nation's dirtiest air but saw pollution trends move in a positive direction.
In 1998, Southern California metropolitan areas had less than half as many poor-air-quality days as they did in 1989. Overall, ozone levels across the United State dropped by about 4 percent during this period, the report said.
David Mintz, the report's team leader, said that while the news is good for Southern California, the area still leads the way in air pollution, with the Los Angeles and Riverside areas seeing about 80 poor air-quality days in 1998.
Nationally, rates fell for all six "criteria pollutants" -- carbon monoxide, lead, ozone, nitrogen dioxide, particulate matter and sulfur dioxide. Ozone saw the smallest decrease.
Among national parks, ozone problems worsened the most in Great Smoky Mountains and Shenandoah in Virginia, with each seeing increases of more than 30 percent over the span of the report, Mintz said.
He said two reasons for the ozone increase in rural areas are pollution migrating from urban areas and emissions from power plants.
"Over the long term, we're doing better," Mintz said. "But as you start looking regionally ... there's cause for concern."
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