Children still run and play in the Kerona neighborhood of Shippingport, Pa., the Beaver County community along the smokestack-studded Ohio River valley.

But not Chad Hysong's kids.

The 35-year-old father of two young girls moved his family west to Ohio five years ago. He wanted to get out of the pollution plumes from all those smokestacks, which, he said, caused them an endless cycle of respiratory problems, pitted his car's paint and chrome, and left a high concentration of arsenic in the soil around his house and in the water in his hot tub.

Others haven't been so lucky, said Hysong's father, Ralph.

"In Shippingport, people don't die of old age. They die of cancer or heart attacks or lung disease," said Ralph Hysong, who is 64 and has a history of heart problems and high blood pressure. "I'm happy Chad and his family got out."

This month, the nation celebrates the 40th anniversary of the federal Clean Air Act and its widespread successes, but health risks and death linger.

A yearlong Pittsburgh Post-Gazette review and analysis of Pennsylvania Department of Health mortality statistics shows that 14,636 more people died from heart disease, respiratory disease, and lung cancer in the region from 2000 through 2008 than national mortality rates for those diseases would predict.

The risks of dying from those three diseases in 13 of the 14 counties exceeded the national rate by a statistically significant number.

Adjusted for slightly higher smoking rates in the region, the total is 12,917 more deaths - or 10 percent - than would be expected from those three diseases in the population of about three million in the 14 counties (Allegheny, Armstrong, Beaver, Butler, Cambria, Clearfield, Fayette, Greene, Indiana, Jefferson, Lawrence, Somerset, Washington, and Westmoreland).

The mortality rates raise a question: Is air pollution a cause?

"The U.S. Environmental Protection Agency still views the region as a [pollution] hot spot," said John Graham, senior scientist with the Clean Air Task Force, a 14-year-old national nonprofit research and advocacy organization focused on air quality and climate issues.

"There have been a lot of air-quality improvements in the region, but they haven't happened at a consistent pace," Graham said. "Based on the latest PM [airborne particulate matter] data, it still ranks as one of the worst urban areas of the country.

"The air is not clean, and it's killing people."

Despite regulatory efforts, the region's air still contains high concentrations of soot and ozone, which is a precursor to unhealthy smog. And most of its population lives in an area that does not meet federal health standards limiting those pollutants.

One reason is the region's high industrialization and reliance on burning the cheap, abundant coal to generate half its electric power. Those emissions add to an already heavy load of fossil-fuel pollution blown into the region from utilities and industries to the west.

The current air pollution could be causing as much as $9.4 billion a year in damage to the health of the region's population, based on a formula developed by Jonathan Levy, professor of environmental health at the Boston University School of Public Health and a member of the EPA's science advisory board staff.

While it's known that the risk of dying from heart and lung diseases and lung cancer is heightened by occupational exposure, socio-economic status, genetic predisposition, and lifestyle factors including smoking, alcohol consumption, diet, and obesity, numerous peer-reviewed scientific studies have also conclusively documented the links to air pollution.

That pollution can come from many sources: coal-burning industries and utilities, vehicle emissions, and other hazardous chemical emissions from industry.

The Post-Gazette numbers show "that the science behind the Clean Air Act is very solid. Sulfur dioxide, nitrogen oxides, and soot are regulated because the real evidence is overwhelming that they can sicken and kill people," Pennsylvania Environmental Protection Secretary John Hanger said. "The emissions numbers are on their way down but not yet at the levels they need to be to protect human health."

The Post-Gazette mapped the mortality rates for heart disease, lung disease, and lung cancer for each of 746 municipalities in the 14 counties and found an irregular pattern of higher rates around many of the region's 16 coal-fired power plants and 150 other companies that the EPA considers major stationary sources of pollution.

The mortality mapping, while not establishing a direct cause-and-effect link to any specific pollution source, shows associations that are consistent with accepted scientific health risk models and formulas used by the EPA and pollution scientists. It indicates that pollution may play as big a role in the region's high mortality rates for those three diseases as Pall Malls, pilsners, and pierogi.

Doug Biden, president of the Electric Power Generation Association, a Harrisburg lobbying group for the industry, said a "whole soup of emissions," including from diesel vehicles and similar mobile sources, contributed to the region's air pollution.

"It's not just the power plants," Biden said. "The EPA relies on a small handful of studies that establish an association between power-plant emissions and these diseases, but an association does not prove cause and blame.

"We understand the concern here, and certainly emissions from power plants are something we take seriously."

Of particular concern are tiny airborne particles known as PM2.5, for particulate matter measuring less than 2.5 microns. Those particles, one-thirtieth the diameter of a typical human hair or smaller, can be breathed deeply into the lungs and are known to cause heart and respiratory sickness and death.

The Post-Gazette's investigation, including interviews with more than 150 people around the region, also found that great uncertainty remains about local air quality. More and better monitoring, scientific review, and study of industrial air pollution by county, state, and federal health and environmental agencies are needed to better understand and pinpoint causes of the region's higher mortality rates.

Director Bruce Dixon said the Allegheny County Health Department's regulatory approach is, of necessity, a "balancing act" between public health and economic realities.

"We could get the air quality of Montana, but we wouldn't have any jobs around here," Dixon said. "The reality is we have the world's largest coke works, steel mills, and a coal-fired power plant, and that's not a common scene across the United States. You wouldn't do that today. You wouldn't colocate that number of emissions sources, and you wouldn't put them in a river valley."

While the higher mortality rates may in part reflect the legacy of decades of dirty industrial pollution, several air-pollution experts said the rates might also signal that existing regulations and enforcement were inadequate.

"Clearly these laws are not working for everybody," said Jan Jarrett, president and chief executive officer of Citizens for Pennsylvania's Future, an environmental advocacy organization. "And the job isn't done in terms of cleaning up the air."