Right on the heels of Pittsburgh's return to the top of the nation's list of most livable cities, at least according to "Places Rated Almanac," comes a ranking that is truly rank.

In the American Lung Association's "State of the Air" report covering 2003-05, Pittsburgh is No. 2 behind Los Angeles on the list of dirtiest metropolitan areas on short-term and annual airborne particle measurement scales.

Though much of the particulate is invisible, its effects are not. Particle pollution is a health risk that cries out for immediate attention. Heart disease, asthma and other respiratory problems are a direct result of the increase in soot.

The lung association says that, in the eastern United States, the increase in electricity generation by coal-fired power plants has raised the level of airborne particle pollutants. Pittsburgh comes by its soot problem mostly by way of its neighbors.

Though unacceptably high in Allegheny County in 2005, the level of particle pollution began to trend downward in 2006 thanks to the installation of emission controls in power plants west of Pittsburgh, according to the county health department. While a promising start, it isn't nearly enough.

Federal guidelines governing particle pollution should be strengthened across the board, regardless of the economic impact. With the exception of Los Angeles, soot levels are down in the west because of tougher emissions standards and the use of innovative technologies implemented by power plants.

Clean air is one of those non-negotiable rights that transcend quality of life, politics and profit motives. When our collective survival is at stake, civic morality dictates swift action.

There was a time when smokestacks in Pittsburgh belched out enough pollution to block the sun. As a region, we got smart and addressed that problem.

Today Pittsburgh sits under clear skies because of actions taken then. We can't solve our soot problem alone, but the Pittsburgh region -- through government leadership, corporate responsibility and citizen pressure -- should work to clean up its own back yard.