He held more than 100 patents, won the most prestigious awards in his field, and died convinced he was a savior of humanity. Decades later, historians began calling him the single most destructive organism in the history of the planet. This episode is a deep dive into Thomas Midgley Jr., the GM engineer whose two flagship inventions accidentally rewired the atmosphere.

We trace the two miracles. First, tetraethyl lead, the anti-knock agent that solved the engine knocking problem and ushered in the era of leaded gasoline, despite a string of suspicious deaths at the Standard Oil Bayway plant and his own bouts of lead poisoning that he kept treating as PR problems. Then, after he was quietly removed as vice president of GM Chemical, his even more consequential second act: chlorofluorocarbons, marketed as Freon, which solved the safety problem in refrigeration by replacing toxic ammonia with an inert wonder gas that turned out to eat the ozone layer.

We also cover the strange end. Polio left Midgley partially paralyzed late in life, and he engineered an elaborate harness of ropes and pulleys to lift himself out of bed. He died entangled in his own invention. The episode closes with the question every modern reader has to sit with: if a mind as brilliant as his could not foresee global lead exposure, ozone depletion, or the link between leaded gasoline and the 20th-century crime wave, what is hiding inside today's miracles?

Subscribe to pplpod for more deep dives into the people who reshaped the world. Topics: Thomas Midgley Jr., leaded gasoline, tetraethyl lead, CFCs, Freon, ozone layer, environmental history, General Motors, unintended consequences.

Source credit: Research for this episode included Wikipedia articles accessed 5/3/2026. Wikipedia text is licensed under CC BY-SA 4.0; content here is summarized/adapted in original wording for commentary and educational use.