Thomas Midgley Jr.

Thomas Midgley Jr. was born in Beaver Falls, Pennsylvania, on May 18, 1889, into a family of inventors, and trained as a mechanical engineer at Cornell. He joined Charles Kettering's research laboratory at Dayton in 1916 and spent his career there and at General Motors — a chemist by practice rather than by training, and an exceptionally effective one, eventually holding more than a hundred patents and the presidency of the American Chemical Society.

His first assignment was engine knock. After years of systematic screening he found in 1921 that tetraethyl lead suppressed it beautifully, and GM marketed it as 'Ethyl', conspicuously omitting the word lead. The dangers were known immediately: workers at the production plants suffered hallucinations and several died. Midgley himself was diagnosed with lead poisoning in 1923, and at a 1924 press conference he poured tetraethyl lead over his hands and inhaled its vapour for a minute to demonstrate its safety, then spent months convalescing. Leaded petrol went on to be burned worldwide until phase-outs beginning in the 1970s, raising blood-lead levels across an entire species.

His second assignment was refrigerant safety. Early refrigerators used ammonia, sulphur dioxide, and methyl chloride, and leaks were killing families in their sleep; after a run of fatal accidents in the late 1920s, GM asked Midgley for something inert. In three days in 1928 he produced dichlorodifluoromethane — CFC-12, trade-named Freon. He demonstrated it at a 1930 American Chemical Society meeting by inhaling a lungful and using it to blow out a candle: non-toxic and non-flammable, in a single theatrical breath. It went into every fridge, air conditioner, and aerosol can on Earth.

The property that made Freon safe made it catastrophic. Nothing in the lower atmosphere attacks a CFC, so the molecules drift intact for decades to the stratosphere, where ultraviolet light frees their chlorine and each atom catalytically destroys on the order of 100,000 ozone molecules — a chain Mario Molina and Sherwood Rowland worked out in 1974, thirty years after Midgley's death. Midgley contracted polio in 1940 and, disabled, engineered a system of ropes and pulleys to lift himself from bed; he was strangled by it on November 2, 1944. The environmental historian J. R. McNeill wrote that he 'had more impact on the atmosphere than any other single organism in Earth's history'. He was, both times, solving the problem in front of him.