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Facing a curious group of reporters, the inventor Thomas Midgley Jr. confidently poured a lead-infused substance over his hands while inhaling its fumes for nearly sixty seconds. “I could do this every day without any ill effects,” he proclaimed.

It wasn’t long before Midgley himself sought medical care. But the broader impact of this demonstration would stretch far beyond his own health concerns.

The year was 1924, and Midgley, a chemical engineer working for General Motors, had orchestrated the stunt to endorse his latest creation: tetraethyl lead, a lead-based additive to gasoline. It seemed to solve a pressing issue for the auto industry — pesky engine knocks caused by the poor fuel quality of the time. Though effective, the additive came at a dangerous price: lead is highly toxic to human beings, particularly children.

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This wasn’t the only legacy Midgley would leave behind. Later, he tackled another hazard: replacing hazardous and volatile substances used in cooling systems like air conditioners and refrigerators. His solution, chlorofluorocarbons (CFCs), proved deadly for the ozone layer, a critical shield against harmful UV radiation.

A full century after that 1924 press event, the planet is still coping with the ramifications of Midgley’s creations. It’s estimated the ozone layer will take another 40 years to fully recover, and shockingly, parts of the world continued using leaded gasoline until 2021—leaving millions grappling with lifelong impacts of lead poisoning.

For a long time, however, Midgley was celebrated as a genius, and his story will be the focus of an upcoming feature film by the writer behind "The Wolf of Wall Street."

Born in Beaver Falls, Pennsylvania, in 1889, Midgley was naturally inclined to repurpose existing substances in unique ways. Even in high school, he found innovative uses for the bark of slippery elm trees to enhance the curve of a baseball pitch—an idea later embraced by professional athletes.

Always carrying a copy of the periodic table, he was determined to find the chemical breakthrough that would define his career. That opportunity came when General Motors tasked him with eliminating engine knocking in 1916.

“It was the beginning of America’s love affair with cars,” said Gerald Markowitz, a history professor at City University of New York. “With Ford’s Model T paving the way, GM collaborated with Standard Oil and DuPont to build engines capable of greater power—if they could solve this engine knock problem.”

Under the guidance of Charles Kettering, another key American inventor, Midgley experimented with thousands of substances—including arsenic, sulfur, and silicon. His relentless quest led to the discovery of tetraethyl lead, soon marketed as “Ethyl.” By 1923, leaded gasoline had launched in Dayton, Ohio, eventually spreading globally.

Lead is an established poison, with no safe level of exposure. According to UNICEF and the World Health Organization, it can severely damage children's development, causing reduced intelligence and behavioral issues. Even today, nearly a million people die annually from lead exposure.

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Despite lead’s dangers being well-known, Ethyl became a commercial triumph. “There were early concerns because people already understood lead’s toxicity,” Markowitz explained. “But industries argued there was no solid evidence car emissions from leaded gas would hurt anyone—which led public health officials, including the Surgeon General, to take no action at a 1925 conference.”

Yet factory workers producing Ethyl experienced severe symptoms almost instantly. “The real crisis arose when those working in tetraethyl lead labs began to suffer from poisoning,” said Markowitz. “Many workers developed psychosis as a consequence of their exposure to lead compounds.”

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To dispel growing fears, Midgley made headlines again in 1924 by covering his hands in Ethyl and inhaling its fumes—a bold public relations move that couldn’t hide the uncomfortable reality: he too was slowly being poisoned.

“Evidence exists from a letter Midgley wrote in January 1923 confessing a mild case of lead poisoning, and he lived with it for the rest of his life,” said Bill Kovarik, a communications professor at Radford University, Virginia. “Such heavy exposure didn’t just go away; it led to a long-term disability.”

After the Ethyl breakthrough, Kettering encouraged Midgley to pivot to another prevalent problem: the search for a safer alternative to highly flammable refrigeration gases like ammonia. By 1930, Midgley had invented Freon, the first CFC, a compound made from carbon, chlorine, and fluorine. Its safety seemed irrefutable, evident in a public demonstration where Midgley dramatically extinguished a candle by exhaling the compound.

Freon’s commercial success fueled a rapid rise in air conditioning, especially in the U.S., and CFCs soon also found their way into aerosols like insect sprays and hair products. Yet, by the mid-1970s, thirty years after Midgley’s death, the devastating impact of CFCs became clear. CFCs had wrecked the ozone layer, especially over Antarctica, threatening life on Earth.

With continued industry resistance, leaded gasoline wasn’t outlawed in the U.S. until 1996 and remained available across much of the world for decades after. Algeria, the final country to ban it, only did so in 2021, and lead-based additives still persist in some aviation fuels. Research in 2022 estimated that half of the U.S. population suffered dangerous lead exposure during childhood. The full extent of health damage remains difficult to establish.

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The Montreal Protocol of 1987 committed to phasing out CFCs globally, leading to their ban by 2010. Although some illegal production continues, the ozone layer is now slowly healing, with full recovery anticipated within 50 years—a rare success in environmental conservation.

“It’s a heartbreaking truth that the number of affected children remains unknown,” said Markowitz. “No amount of lead is safe in a child’s body, and millions—perhaps hundreds of millions—had their development harmed by exhaust gases laden with lead that tainted streets and soil.”

Midgley’s final years were marred by tragedy. In 1940, he contracted polio, leaving him severely disabled. Engineering one more invention, he devised a system of pulleys and strings to lift himself from bed. But on November 2, 1944, Midgley died after becoming entangled in the device—strangled by his own creation.

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For years, many viewed this as the ultimate ironic tragedy—an inventor ruined by his invention. However, Kovarik suggests the reality may be far grimmer.

“The official cause of death was suicide,” he said. “His intense guilt played a role—industries hailed him as a brilliant mind, but in hindsight, his actions were reckless. The lead poisoning likely exacerbated a growing psychosis.”

Even in his later life, Midgley received accolades. He was awarded the Perkin Medal by the Society of Chemical Industry in 1937, and in 1941, the American Chemical Society honored him with the Priestley Medal, further electing him president the year of his death.

In a 1947 biographical tribute, Midgley’s mentor Kettering offered only admiration, concluding that Midgley’s legacy was “a rich gift from a life of ceaseless creativity and purpose.”

While other inventions, such as TNT, also turned out to have unintended deadly consequences, Midgley’s dual legacy of harm is unique. While some might label him an environmental villain, scholars suggest his role was more complex.

“He was merely a cog in the industrial machine,” Kovarik reflected.

Markowitz agreed. “This was corporate-driven research. If Midgley hadn’t made these discoveries, someone else surely would have,” he remarked.

The blind pursuit of progress at any cost defined much of the early 20th century, Markowitz added. “It wasn’t until the 1960s and ’70s, spurred by the environmental movement, that people began to critically assess where unchecked technological growth could lead.”

“It had a sobering effect. But for the first half of the century, few voices questioned the idea that progress was our greatest good.”