For years, the residents of Diamond, Louisiana, lived with an inescapable acrid, metallic smell -- the "toxic bouquet" of pollution -- and a mysterious chemical fog that seeped into their houses. They looked out on the massive Norco Industrial Complex: a maze of pipelines, stacks topped by flares burning off excess gas, and huge oil tankers moving up the Mississippi. They experienced headaches, stinging eyes, allergies, asthma, and other respiratory...