Thomas Midgley Jr.

Jordan Healey, Science and Technology editor, looks at the life of one of the most controversial scientists and inventors of the twentieth century.


Thomas Midgley Jr. was a mechanical engineer and chemist born in Beaver Falls, Pennsylvania on May 18th 1889. He was also a prolific inventor and during his lifetime he had more than one hundred patents to his name. However, his legacy has been almost completely tarnished after two of these inventions have led to the claim by many – including environmental historian J. R. McNeill – that he has had ‘more impact on the environment than any other single organism in Earth’s history’. Pioneering the use of lead based additives in gasoline as well as synthesising the first CFC (dichlorodifluoromethane also known as Freon) are amongst his most iconic achievements, both of which have disastrous long term effects on public health and the environment. Midgley’s two most revolutionary inventions have been globally restricted or banned since our understanding of them has evolved over the past few decades for many reasons.

The use of tetraethyl lead (TEL) as an additive to gasoline was developed by Thomas Midgley Jr. during his work as a researcher for General Motors in 1921. His job there was to look into ways of increasing fuel efficiency and reducing the effects of engine ‘knock’. Although using lead was well-known for being poisonous (Midgley himself fell ill to lead poisoning during his work for General Motors), its continued use led to many incidents involving exposure to lead in the workplace. This includes an incident when five workers at a TEL plant in New Jersey died and thirty-five more were hospitalised. This occurred in 1924 and even made it to the front page of the New York Times. It was not until the 1970s, however, that Lead became decreasingly used as an additive in fuel; it had almost completely disappeared from the market by 1986 (due to its negative effect on catalytic converters not the fact it is highly toxic, kills people and is linked with birth defects amongst many other reasons). Many people believe that the Public Relations team of General Motors deliberately supressed public fear and acted in a misleading way when naming a joint company between themselves, Du Pont and Standard Oil of New Jersey. After the initial name ‘Ethyl Gasoline Company’ was changed to simply ‘Ethyl’ it became quite clear that they had no intentions of letting people know that harmful products were given off by chemical reactions in their cars.

The second of Midgley’s infamous inventions was that of Freon; the first CFC, which was synthesised within only three days of Midgley being commissioned by General Motors to find alternative refrigerants to those already in use. CFCs (chlorofluorocarbons) are now known to be the main cause of ozone depletion. In 1930, when Freon was first used as a refrigerant, its damaging effects on the atmosphere were unknown and it was considered far safer than sulphur dioxide, ammonia and methyl chloride which were being used before. Freon seemed perfect; it was non-toxic, non-flammable, non-corrosive and safe to breathe.  Over the next fifty years CFCs were widely used in millions of homes all across the world. It was not until 1973 that CFCs were detected in the atmosphere and it took a further eleven years to discover the ozone hole over Antarctica that was caused by extensive use of these compounds (dthis hole is not expected to recover until 2050 since CFCs remain present in the stratosphere for many years). Following the Montreal Protocol in 1987 their use became phased out and by 2005 legal global production had ceased entirely.

Despite the damaging impacts of some of his biggest works, Thomas Midgley Jr. made many contributions to help progress our understanding of chemistry particularly through his study of rubber and more specifically vulcanisation (the addition of certain compounds to polymers in order to increase durability). He wrote 19 published papers on this subject alone. He also played an important role in developing methods used to extract bromine contaminants from water.

He will almost certainly remain a controversial figure in science for his contributions for many years to come, especially considering how he was complicit in selling and managing his potentially lethal lead-based products while fully aware of their repercussions. His ozone depleting invention, however, was well-intended but could have probably been researched more in-depth before being made widely available. Many people will probably argue that his death at the hands of his own invention in 1944 epitomises poetic justice. After contracting polio and being left unable to walk, he created a rope and pulley system to help make him more mobile, however he was ultimately strangled by the device long before we fully understood the impact his work has had on humanity.