Chlorofluorocarbons are also not very abundant—they constitute only about one part per billion of the atmosphere as a whole—but they are extravagantly destructive. One pound of CFCs can capture and annihilate seventy thousand pounds of atmospheric ozone. CFCs also hang around for a long time—about a century on average—wreaking havoc all the while. They are also great heat sponges. A single CFC molecule is about ten thousand times more efficient at exacerbating greenhouse effects than a molecule of carbon dioxide—and carbon dioxide is of course no slouch itself as a greenhouse gas. In short, chlorofluorocarbons may ultimately prove to be just about the worst invention of the twentieth century.

Midgley never knew this because he died long before anyone realized how destructive CFCs were. His death was itself memorably unusual. After becoming crippled with polio, Midgley invented a contraption involving a series of motorized pulleys that automatically raised or turned him in bed. In 1944, he became entangled in the cords as the machine went into action and was strangled.