Jan. 14--A federal judge ordered Tuesday that the Tennessee Valley Authority install pollution controls on four power plants and substantially reduce pollutants that cause respiratory problems and swath North Carolina mountains in a whitish haze.

U.S. District Judge Lacy Thornburg, ruling in a nationally watched case, said North Carolina had shown that untreated air pollution from three power plants in eastern Tennessee and one in Alabama harmed citizens in North Carolina and posed a public nuisance. Thornburg said the TVA had failed to install pollution controls in a timely manner, and he ordered installation of such controls.

The court rejected North Carolina's request to require that TVA install controls on seven other coal-burning plants more distant from North Carolina, saying the effect of pollution from those plants was not measurable in North Carolina.

"I am pleased that the court ordered TVA to clean up the air pollution coming from its plants closest to North Carolina," Attorney General Roy Cooper said in an interview. "This will help our air, our health and our travel and tourism economy. All of our evidence showed that these four plants were doing the greatest damage to North Carolina."

North Carolina sued TVA in 2006, contending the pollution from its 11 coal-burning power plants in Tennessee, Alabama and Kentucky wafting across the border caused respiratory problems and threatened the health of millions of people. The state's environment and economy also are harmed by TVA's emissions, which pose a public nuisance, the state argued.

TVA, a federal government agency, operates the nation's largest public electricity-producing system, providing power to large portions of Tennessee, Kentucky, Mississippi and Alabama and small parts of western North Carolina and southwestern Virginia. TVA's 11 coal-burning plants range from 35 to 50 years old.

Authority officials disputed claims that their plants harm North Carolinians and fought hard to get the lawsuit dismissed. The American Lung Association and 19 states, including New York, California, Ohio and South Carolina, joined North Carolina in opposing TVA's effort to dismiss the lawsuit during the appeals process.

"TVA is disappointed by the court's decision," said John Moulton, a TVA spokesman. "We're continuing to analyze it. In the meantime, TVA is committed to continuing its work to improve the region's air quality."

Speedup ordered

Pollution controls are in place or on the drawing board at three of the four plants addressed in the court order.