A study that for the first time links pollution from coal-fired power plants, factories and diesel trucks to a greater risk of lung cancer has heightened the importance of trying to clean the air of tiny soot particles in areas such as Pittsburgh.
But that higher profile won't make reducing the unhealthy levels of airborne particles any easier.
In southwestern Pennsylvania, old and dirty power plants in the Ohio River valley, prevailing southwesterly winds and a valley and ridge geography that traps pollutants combine to produce high concentrations of the fine particles and complicate efforts to reduce them.
"We don't have all the answers yet -- there are lots of studies going on -- but it's pretty clear that Pittsburgh will not be able to solve its particle problem on its own," said Marcia Spink, associate director for air programs at the U.S. Environmental Protection Agency's Philadelphia office.
"It will take a regional approach and that means controls on emissions from neighboring states."
Studies have found that one-third to one-half of the fine particles in southwestern Pennsylvania's air are ammonium sulfates -- so-called "secondary particles" -- that are formed when sulfur dioxide gas emitted by power plants combines over time and distance with ammonia and water in the atmosphere.
It's easier to define the problem than to fix it, though.
With the cost of adding emission control equipment to old coal-burning power plants estimated at $70 million to $100 million for each plant, and President Bush's administration reluctant to tighten environmental controls, it's hard to predict how or when the air will get healthier.
"There are political and economic and practicality questions about what gets done and when," said John Bachmann, science adviser on particulates for the U.S. Environmental Protection Agency.
But what if those problems could be put aside?
"If I was God -- boom! -- one of the first things I'd do would be to reduce power plant emissions. Then -- poof! -- I'd change diesel buses to clean running buses, and -- poof! -- I'd change over the diesel truck fleet to the cleaner-running engines," Bachmann said.
To design, engineer and install a scrubber or similar pollution control device on a power plant is a three-year process, for example, and a total turnover of the interstate trucking fleet could take a decade or more.
Retrofitting mass transit bus fleets for cleaner emissions can be accomplished more quickly -- New York City for one has done it -- but it is costly.
Still, a study published in the Journal of the American Medical Association yesterday that concluded that people living in heavily polluted urban areas were 16 percent more at risk of dying of lung cancer has lent a sense of urgency to the debate about cleaning the air of fine particles.
Previous studies by Harvard University's School of Health and the American Cancer Society established strong links between cardiopulmonary diseases such as heart attacks, strokes and asthma, and the fine particles less than 2.5 micrometers in size -- one-50th the diameter of a human hair -- which can be drawn deep into the lungs with every breath.
The latest study, by Arden Pope, a Brigham Young University epidemiologist, was the first to link fine particles to cancer mortality.
"Why is it when cancer is mentioned that it is somehow more legitimate a concern than other morbidity from lung disease and heart disease that is already established?" said Roger Westman, Allegheny County Health Department division manager for air quality.
He said he'd like to see some confirmation from other studies.
In Allegheny County, the average annual concentration of fine particles in 2000 was 15.9 micrograms per cubic meter -- higher than the federal health-based standard of 15 micrograms. And eight of the 12 monitoring stations also exceeded the standard.
"It's not going to be an easy standard to meet, especially since every [monitoring] station has to be below the standard," Westman said. "It's not a question of how we're going to fix this today. We don't have immediate solutions."
Westman said fine particulates could be reduced by tightening emission controls on power plants, boilers and coke plants, but the cost would be high.
"There's got to be a national effort to look at the pollutants," he said, "and then a strategy devised on how to address the problem."
