IN THE EARLY 1900s, London had long been known for its smoky, polluted air. The smoke of burning coal mixed with the fog that often fell on London, turning the air dark, murky, and dangerous to breathe. On December 5, 1952, this London "smog" caused the deadliest environmental catastrophe in history.

A funeral director named Stan Cribb witnessed the beginning of the "Killer Fog of '52" and remembers it clearly even fifty years later. He has led thousands of funeral trains through the smoggy streets of London, but he says that 1952 was the worst smog he had ever seen. Describing the first gray wisps of the smog, he says, "You had this swirling like somebody had set a load of car tires on fire."

On Friday, December 5, Stan Cribb and his elderly uncle were driving to a wake, with a...