A yearlong Pittsburgh Post-Gazette investigation has found that air pollution problems in western Pennsylvania remain far from being solved.

Throughout the region are neighborhoods where residents report "clusters" of death they blame on pollution. But they remain frustrated by the lack of government review.

Many of Western Pennsylvania's 16 coal-fired power plants have operated for months and even years in violation of their air or water pollution permits and paid relatively small penalties, the Pittsburgh Post-Gazette found in a review of state and federal data.

The airborne transport of nearly invisible particles from power plants in Ohio and West Virginia are significant contributors to air quality and public health problems in western Pennsylvania.

Air pollution control technology is removing more and more airborne pollutants from utility emissions. But growing fly-ash disposal sites, as well as plans to dump it into water, are becoming a serious and growing health concern.

The debate over particle pollution centers on whether smokestack pollution could be less harmful to humans than vehicle pollution.

The labor union at the Bruce Mansfield coal-fired power plant in Shippingport, Beaver County, said that nearly half of the 360 workers it represents have been diagnosed with pulmonary and respiratory ailments and malignancies.

Some experts say that if the cost of health damage were part of the cost of electricity, coal would lose its price advantage.