In the early 20th century, Thomas Midgley Jr. personally demonstrated the safety of leaded gasoline and CFC refrigerants, leading to their commercial success.
In 1924, in front of journalists, the American inventor Thomas Midgley Jr. poured a lead additive onto his hand and inhaled the fumes for about a minute. “I could do this every day without any health problems,” he claimed. However, Midgley later required medical treatment. This act not only impacted his own health but also resulted in far more catastrophic consequences.
Inventor Thomas Midgley Jr. was once celebrated for developing leaded gasoline and Freon. (Photo: Corbis).
Midgley left a mark with another destructive invention, as a solution to the need for a replacement for toxic and flammable gases used in refrigeration and air conditioning. He discovered that CFC, or chlorofluorocarbon, was an ideal and harmless substitute for humans, but he was unaware that it would destroy the ozone layer.
Both of Midgley’s inventions were praised for decades. However, 100 years after the 1924 press conference, the Earth is still recovering from their negative impacts.
Leaded Gasoline
One of the biggest challenges the automotive industry faced in the early 20th century was engine knocking—small explosions in car engines caused by poor gasoline quality, creating unpleasant sounds and potentially causing damage. The task of solving the engine knocking problem was assigned to Midgley while he was a chemical engineer at the American automobile manufacturer General Motors in 1916.
Under the guidance of Charles Kettering, another famous American inventor and head of research at General Motors, Midgley researched thousands of substances including arsenic, sulfur, and silicon to find a compound that could be added to gasoline to reduce knocking. Ultimately, he discovered tetraethyl lead, a lead derivative marketed simply as Ethyl. Leaded gasoline was first sold in Dayton, Ohio in 1923, and then spread worldwide.
The Ethyl blend containing lead was commercially successful. (Photo: Colin Creitz/The Enthusiast Network).
Lead is highly toxic, has no safe exposure level, and can negatively impact the development of children, causing cognitive impairment and behavioral disorders, according to the United Nations Children’s Fund (UNICEF). It is estimated that about 1 million people still die each year from lead poisoning, as reported by the World Health Organization (WHO).
The toxicity of lead was widely known when Midgley added it to gasoline, but that did not prevent Ethyl from achieving commercial success. “There were warnings because lead was considered a poison. However, the automotive industry’s argument at the time was that there was no evidence showing that lead escaping from car exhaust harmed humans,” said Gerald Markowitz, a history professor at the City University of New York.
However, Ethyl production workers quickly suffered negative effects. After the 1924 press conference, Midgley himself also suffered from lead poisoning.
“Midgley wrote in a letter in January 1923 that he had been slightly poisoned by lead, and indeed he suffered from lead poisoning for the rest of his life. This condition does not really go away once you absorb that much lead into your body. It is a serious and long-term issue,” stated Bill Kovarik, a professor at Radford University.
CFC Refrigerants
A few years after the invention of Ethyl, Midgley, once again encouraged by Kettering, began developing a non-toxic, non-flammable substitute for refrigerants, such as ammonia used in refrigeration devices and air conditioning, which had led to many fatal accidents in the 1920s.
Midgley discovered Freon—a derivative of methane comprising carbon, chlorine, and fluorine atoms—and the first CFC compound. In a public demonstration in 1930, he inhaled this gas and blew out a candle, demonstrating its safety.
After World War II, manufacturers frequently used CFCs in a variety of products, such as spray cans. (Photo: Joe Sohm/Visions of America/Universal Images Group).
Freon, along with subsequent CFCs, achieved commercial success and led to a significant increase in air conditioning use in the United States. After World War II, manufacturers began to regularly use CFCs in various products, including pesticides and hair sprays.
Decades after the introduction of CFCs, scientists discovered that these compounds had created a hole in the ozone layer above Antarctica. If left unchecked, the hole would expand to a level that threatened all life on Earth.
Long-term Impact
By 1996, leaded gasoline was phased out in the U.S., and then eliminated worldwide. The last country to do this was Algeria, which continued selling leaded gasoline until 2021. A study in 2022 estimated that half of the current U.S. population had been exposed to dangerous lead levels as children, but the health costs to the world are difficult to quantify.
In 1987, the Montreal Protocol was signed to gradually eliminate CFCs from 1989 to 2010, after which these compounds were banned. The ozone hole is improving and may heal, but it will take about another half-century.
