Last month’s spectacular explosions at a large Philadelphia oil refinery complex injured five workers, terrorized city residents and drove up gasoline prices. But the impact could have been vastly worse had the explosions triggered a release from the refinery’s huge inventory of toxic hydrogen fluoride — up to 420,000 pounds’ worth, according to information the company filed with the Environmental Protection Agency in 2017. That disaster, had it occurred amid the chaos on the morning of June 21, would have imperiled hundreds of thousands of people living within a few miles of the plant.
