"PHILADELPHIA -- The region's refineries are behemoths, enriching the economy, but also ranking among the region's top air polluters.
They emit a brew of contaminants, from chemicals that cause cancer to those that help make smog.
They've had difficulty meeting emissions limits, chalking up 143 'formal enforcement actions' in the last five years and more than $12 million in penalties. All the companies are under federal consent decrees to upgrade their equipment.
Last Sunday's explosion and fire at Sunoco's Marcus Hook oil refinery was one of those signature events, like a spill, a reminder of the potential for major accidents at such facilities.
But day in and day out, area refineries have a significant impact."