Cautionary Tales with Tim Harford - The Inventor who Almost Ended the World (Classic)

Episode Date: May 22, 2026

Thomas Midgley's inventions caused his own death, hastened the deaths of millions of people around the world, and very nearly extinguished all life on land.  Midgley and his employers didn't set out to poison the air with leaded gasoline or wreck the ozone layer with CFCs - but while these dire consequences were unintended... could they have been anticipated? For a list of sources, see the show notes at timharford.comSee omnystudio.com/listener for privacy information.

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Learn how podcasting can help your business. Call 844-844-I-Hart. Pushkin. Thomas Midgely Jr. was born on College Hill in Beaver Falls, Pennsylvania, May 18, 1889. His father, Thomas Midgley, Sr., was a prolific inventor in a variety of fields, but notably that of automobile tires. A eulogy for an inventor, a hero of industrial science, who changed the world,

and who died tragically young, aged just 55. Thomas Midgley Jr. studied mechanical engineering, but he was just as fascinated by chemistry. As a young researcher employed by General Motors, Midgley took to carrying a copy of the periodic table around in his pocket to inform his quest for new ideas. By the end of his life, Midgley had accumulated over a hundred patents. We're going to hear about three of his inventions.

In 1916, Midley became a member of our research staff and began then his long association with me and his remarkably productive career in research. The eulogist is Charles Boss Kettering, himself an inventor of some renown. Kettering was Thomas Midgely's boss in the General Motors Research Department. He went on to become a lifelong friend, mentor and business associate, as the two men built lucrative careers with General Motors and the DuPont Corporation.

What do you want me to do next, boss? That simple question and the answer to it turned out to be the beginning of a great adventure in the life of a most versatile man. Versatile indeed. The brain children of Thomas Midgley touched many areas of life. This pudgy bespectacled inventor

seemed to personify the mid-20th century ideal of progress, as summed up by DuPont in their famous 1930s advertising slogan. Better things for better living through chemistry. In his eulogy, Boss Kettering runs through Midgley's long list of accomplishments. President of the American Chemical Society, winner of the Nichols Medal,

the Perkin Medal, the Priestley Medal, the Willard Gibbs Medal, the Longstrath Medal, honorary doctorates from the College of Worcester and the Ohio State University. Kettering quotes the citation from Ohio. state. Midgley contributed so greatly to more pleasant and efficient living. He has made science a liberator, and we rejoice with him in the satisfactions that must be his in seeing the fruits of his labour. Posterity will acknowledge their permanent value. Posterity, alas, was not as kind to Midgley as his many admirers had expected. But they were absolutely right to say that he

would change the world. He did. He made it much, much worse. I'm Tim Harford, and you're listening to Cautionary Tales. What do you want me to do next, boss? One day when Thomas Midgley asked that question of Charles Kettering, the boss had a problem he wanted Midgley to solve. The problem had to do with refrigeration. At the time, people didn't have fridges at home. It was too dangerous. The chemicals you needed for the cooling coils were either toxic or flammable, so refrigeration was mainly used in industrial settings by trained personnel. Even then, accidents were common. Kettering wanted Midgley to invent a way to cool things safely. Midgley took the periodic table out of his pocket. He soon zeroed in on fluorine as a promising element for creating a

compound that might have the right properties, as Ketwing's eulogy recalls. He and his helpers prepared such a compound. Dichlority fluoromethane. It proved to have just the properties required. It is highly stable, non-inflammable, and altogether without harmful effects on man or animals. Dichloro-difloromethame. It did seem to be altogether without harmful effects.

Midgley tested this by replacing. all the nitrogen in air with dichloro-difloromythane and seeing what happened to animals who breathed it in. Happily for the animals, they were completely fine. Midgley wasn't just an inventor, he was a showman. He presented his new product in a dramatic lecture to the American Chemical Society.

Midgley lights a candle. He produces a container of dichloro-difluoromethane. He sucks it in, a long, deep gulp filling his lungs. And then, slowly and gently, he breathes out over the candle. The flame goes out. It's a bravura performance. Dichloro-difluoromethane belongs to a class of chemicals called CFCs, or chlorofluorocarbons. Under Midgley's guidance,

General Motors and the DuPont Corporation start to produce a whole range of CFCs. They give them the trade name, Fri-on. Thanks to these new, non-hazardous coolants, people soon had refrigerators in their own homes. That was a game changer. Food stayed fresh. The Housewives of America could spend less time endlessly shopping for groceries. Food poisoning was easier to avoid, and it wasn't just fridges, air-conditioners too. Even better, it soon turned out that CFCs had uses beyond cooling.

They were ideal for making aerosol sprays, insect repellents, air fresheners, hairspray, deodorants. It was just like DuPont said. Better things, for better living, through chemistry. In the summer of 1973, nearly three decades after Thomas Midgley's untimely death, a chemistry professor named Sherwood Rowland welcomes a new post-doctoral researcher to his team at the University of California, Irvine. Mario Molina is from Mexico.

He's 30 years old, and he needs Professor Rowland to give him a project to work on. Roland recalls something he heard over coffee at a conference the previous year, about a precise new way of measuring trace gases in the atmosphere, gases like dichloro-difluoromethane. It turns out that CFCs are present in the air around us at 230 parts per trillion. That's like detecting a drop of gin in a swimming pool of tonic.

Roland is intrigued to hear that. Not because the amount sounds so small to him, but because it sounds so big. He knows that it's only a few decades since CFCs started to be manufactured on an industrial. scale. Not much more than that dropful can ever have been produced. Roland is a radiochemist. He studies how particles react and decay. Most chemicals break down in the environment sooner or later, but CFCs just seem to be hanging around. So he makes a suggestion to Mario Molina. Why don't you look into CFCs? Melina recalls, we thought it would be a nice, interesting academic exercise.

We both knew that these CFCs were rather stable, so there was nothing obvious that would damage them soon after they'd be released. That's about as much as I knew at the time. If CFCs aren't interacting much with anything in the atmosphere close to Earth, Molina reasoned, they'll eventually drift upwards to the stratosphere, where the air is thinner. It would take decades, but they'd get there. When they did, they'd encounter more.

ultraviolet B waves from the sun. And maybe that would cause the CFCs to break down because UVB waves are pretty destructive. They're the main reason why too much sunshine can give you skin cancer. In fact, if the Earth had no protection from UVB radiation, life on land might not be possible. What does protect the Earth? The ozone layer.

Ozone is a gas made from oxygen atoms Up in the stratosphere, a thin layer of ozone blocks most of the sun's UVB radiation. Mario Molina sat down to work out what would happen to a CFC molecule when it drifts up to the stratosphere. It would get hit by a wave of UVB radiation. That would knock off the chlorine atom. The chlorine atom would soon meet an ozone molecule. When it did, it would split the ozone apart and form oxygen and chlorine monosum. monoxide instead. But that's not the end of the story, because chlorine monoxide isn't stable.

It breaks down quickly. That frees up the chlorine atom again to take out another ozone molecule, and the cycle repeats. Chlorine atoms pinballing around the stratosphere, popping ozone as they go. Molina was intrigued by this, but not alarmed. After all, there weren't that many CFC molecules in the atmosphere. It was a drop in a swimming pool. They couldn't possibly destroy enough of the ozone layer to cause a problem. Could they? Molina got the data showing how much CFC gas had been produced. He sat down with a pencil, paper, and a calculator, and did the sums.

Oh, that can't be right. He checked them. He checked them again and again. He checked them a dozen times. That night, when he got home, Molina's wife, asked how his day had been. The work's going well, Malina said, but it looks like the end of the world. Cautionary tales. We'll be back in a moment. Canadian women are looking for more. More to themselves, their businesses, their elected leaders,

and the world are out of them. And that's why we're thrilled to introduce the Honest Talk podcast. I'm Jennifer Stewart. And I'm Catherine Clark. And in this podcast, we interview Canada's most inspiring women. Entrepreneurs, artists, athletes, politicians, and newsmakers, all at different stages of their journey. So if you're looking to connect, then we hope you'll join us. Listen to the Honest Talk podcast on Iheart Radio or wherever you listen to your podcasts. Run a business and not thinking about podcasting, think again. More Americans listen to podcasts than ads supported streaming music from Spotify and Pandora. And as the number one podcaster, IHearts twice as large as the next two combined. So whatever your

customers listen to, they'll hear your message. Plus, only IHeart can extend your message to audiences across broadcast radio. Think podcasting can help your business. Think IHeart. Streaming, radio, and podcasting. Call 844-844-I-Hart to get started. That's 844-844-I-Hart. At the University of California, Irvine, Mario Melina tracks down Sherwood-Roland.

I may have found something important. Roland checks Molina's sums. He checks them again. That can't be right. But it was. The CFCs drifting slow. up towards the stratosphere were a ticking time bomb. Barely 40 years had passed since DuPont started to manufacture their CFCs

under the Fri-On brand on an industrial scale. That wasn't long enough to expect any obvious impacts yet, but more and more CFCs were being produced every year. If that continued, what might it mean by, say, the middle of the 21st century? Malina and Roland calculated that up to half the ozone layer could disappear. As Molina had put it, it looked like the end of the world. The two scientists wrote up their research. They published it in Nature in the summer of 1974.

And hardly anyone noticed. A few reporters got in touch from local newspapers. That was nice, but this wasn't really a local story. An executive from DuPont found Sherwood Rowland. I read your paper. I was appalled. Thanks for getting in touch. It is appalling. Throughout your paper, you talk about Friand. Don't you know that Friand's a DuPont registered brand name?

You need to refer to CFCs generically, not Frion specifically. I have to tell you, we take this very seriously. Oh, okay. Roland and Molina were dispirited. They'd discovered the end of the world, and nobody cared. They looked for another opportunity to get attention. The annual meeting of the American Chemical Society was coming up, the very same event that Thomas Midgley had wowed 44 years earlier

by filling his lungs with dichloro-difluoromethane and softly extinguishing a candle. Roland and Molina submitted their paper to the annual meeting. But lots of papers get submitted, so it's the job of the American Chemical Society's news manager to decide which papers to publicize. Her name was Dorothy Smith. She decided to go big, much to the displeasure of DuPont. Hello? I've just seen your press release.

You're making a big thing of this paper on CFCs and ozone. Yes, it seems important. We think it's an insignificant story. A lot of people are interested. Dorothy Smith stood her ground. She put Roland and Molina on stage at a press conference and finally their work started to gain some traction. Environmental activists called for a ban on CFCs.

A few politicians took up the cause, but the industry fought back. Yes, the scientific theory seemed sound, but that's all it was. Theory. No Ozo-O-Zo. depletion has ever been detected, despite the most sophisticated analysis, all ozone depletion figures to date are computer projections based on a series of uncertain assumptions.

The initial burst of attention slowly began to fade. Roland and Molina kept speaking out, but fewer and fewer people were bothering to listen. Progress towards banning CFCs ground to a halt. It was clear that only one thing might reboot the interest of the world's governments. Hard evidence of damage to the ozone layer. But if it took decades for CFCs to drift up to the stratosphere, the first ones to be manufactured would only just be making it there. Would the evidence come in time to avert disaster? We'll pick up the story of CFCs and the ozone layer,

But I promised you three inventions by Thomas Midgley, and as we'll see, those three inventions have a theme. That theme? Unanticipated consequences. I mentioned that Thomas Midgley died young. How did he die exactly? Boss Kettering's eulogy tiptoed around that delicate question. In the early fall of 1940,

Midgley was struck by an acute attack of poliomyelitis, which deprived him at the use of his legs and made him a semi-invalid. Midley died unexpectedly on November 2nd, 1944, at the age of 55. Confined to his bed by polio, Midgley had applied his inventive mind to devising a series of pulleys and ropes by which he could move himself around. He died unexpectedly when a rope in this device got wrapped around his neck and strangled him. So one of Midgeley's inventions had ended up killing him,

and another was going to destroy the ozone layer and fry the planet. It's fair to say that unanticipated consequences is the right description for both these inventions. The phrase unanticipated consequences was coined a few years before Midgeley's death in a much-cited article by the great American sociologist Robert K. Merton. That article was called The Unanticipated Consequences of Purposive Social Action. Throughout history, Merton argued, philosophers have grappled with the idea of unanticipated consequences

using various different words to describe it. But nobody had thought systematically about how unanticipated consequences come about. Merton set himself the task of categorizing all the possible ways in which our actions might backfire. Simple error is one way we might get unanticipated consequences. We think we know what will happen, but we're wrong. Another is what Merton called the imperious immediacy of interest.

Roughly speaking, we're so keen to solve some pressing problem that we don't much care what else might happen down the line. And then there's ignorance, when we don't have the knowledge that would be necessary to anticipate what might happen. In some cases, that might be because we haven't put in the time and energy that would be necessary to get that knowledge. Or maybe the situation is so novel we can't imagine what we might need to know.

That's a good description of what happened with CFCs. Midgley had tried to get some knowledge about potential risks by making animals breathe in dichloro-difluoromethane, but the interaction with ozone came completely out of the blue. This phrase of Robert K. Merton, unanticipated consequences, has a twist. To find out what it is, we need to turn to the third of Thomas Midgley's disastrous brainwaves, arguably the worst of all. It came again from that fateful question.

What do you want me to do next, boss? This time, the problem Charles Kettering wanted Midgley to solve was engine knock when you rev your car and it sounds like you're firing a machine gun it's not a common sound nowadays but it blighted the lives of early motorists General Motors wanted to invent a product

that would stop it but nobody even understood why it happened Thomas Midgley worked it out in an internal combustion engine a piston in a cylinder compresses a mixture of air and fuel until a spark plug ignites it. Engine knock happens when the mixture explodes

before the piston has compressed it fully. It's not just an unpleasant noise. It can damage the engine. But where would you even start to look for a solution? Ketwing and Midgley talked it over. We thought that maybe if the fuel were coloured red, it would absorb more radiant heat and evaporate more completely,

thus preventing the rough combustion. This theory came to us then because we both happened to know that the leaves of the trailing Arbutus are red on the back and that they grow and bloom under the snow. Midgley went to a chemist's shop and brought iodine. He put the iodine in some fuel, which turned it red, and he ran the engine.

No knock. Midgley and Kettering were astonished, but was it really the colour red that was stopping the knock? Middley tried other ways of dyeing fuel, but with no success. Apparently it wasn't the red colour, but something else about the iodine. The leaves of the trailing arbutus had been a red herring. Midgely then tried ethydride, which has iodine, but no colour. It stopped the knock just as well.

Unfortunately, it also corroded the engine. Undeterred, Midgely pulled the periodic table from his pocket. pocket and began to work his way through it. Many anti-knock agents were discovered along the way. Compounds of iodine, of nitrogen, of phosphorus, of arsenic, of antimony, of selenium, of tellurium. But everyone had some limitation or shortcoming, which prevented it from being used in a practical way.

Eventually, Thomas Midgley's perseverance paid off. He discovered something that he could add to gasoline, the way. would stop engine knock without damaging the engine. Tetraethyl lead. Thomas Midley had invented leaded gasoline. Because of Midley's invention, I'm about five IQ points stupider than I would otherwise have been. And so are you, if you're around my age or older,

because you too will have spent your childhood inhaling fumes of leaded gasoline from car exhausts. The air pollution messed up brain development for whole generations of kids, and it caused cancers and heart disease and strokes. It's estimated that leaded gasoline hastened tens of millions of deaths. Leaded gasoline completes an astonishing trifectar. Thomas Midgley invented a rope and pulley device that killed him, an additive for fuel that killed lots of other people,

and a refrigerant that was on course to white. out life on earth altogether. How unlucky can one man be? But luck isn't the whole story. Women are looking for more. More to themselves, their businesses, their elected leaders, and the world are out of them. And that's why we're thrilled to introduce the Honest Talk podcast. I'm Jennifer Stewart.

And I'm Catherine Clark. And in this podcast, we interview Canada's most inspiring women. Entrepreneurs, artists, athletes, politicians, and newsmakers. all at different stages of their journey. So if you're looking to connect, then we hope you'll join us. Listen to the Honest Talk podcasts on IHeartRadio or wherever you listen to your podcasts.

Run a business and not thinking about podcasting, think again. More Americans listen to podcasts than ad-supported streaming music from Spotify and Pandora. And as the number one podcaster, IHearts twice as large as the next two combined. So whatever your customers listen to, they'll hear your message.

Plus, only IHeart can extend your message to audiences across broad. podcast radio. Think podcasting can help your business. Think IHeart. Streaming, radio and podcasting. Call 844-844-I-Hart to get started. That's 844-844-I-Hart. In the early 1980s, the radio chemist Sherwood Rowland and his colleague Mario Molina kept on talking about the danger of CFCs to the ozone layer. Nobody wanted to listen. Roland became more and more exasperated. What's the use of having developed a science well enough to make predictions if, in the end,

all we're willing to do is stand around and wait for them to come true? The predictions, however, were all too easy for the industry to dismiss. Remember the line from DuPont. All ozone depletion figures to date are computer projections based on a series of uncertain assumptions. Only actual evidence of damage to the ozone layer would get, CFCs back on the agenda. But the evidence would be hard to come by. The first CFCs to be produced decades earlier would only just have reached the stratosphere. If they were starting to reduce the levels of ozone, that might be hard to see for a couple of reasons. First, ozone levels fluctuate

naturally. Second, there are different ways to measure ozone from the ground, from satellites, from special instruments tied to helium balloons, which were most accurate, no one was entirely sure. Tantalizing hints of evidence began to emerge. Some Japanese researchers sent balloons to the stratosphere. The ozone readings came back worryingly low, but you really needed a long-term series of data points to establish there was a trend.

The Japanese team didn't have that. But someone else did. For 25 years, an obscure organisation called the British Antarctic Survey had been toiling away on a shoestring budget, sending researchers to a remote outpost in Antarctica to measure all sorts of things. They weren't looking for anything in particular.

They'd just like to collect data in case it ever happened to show anything interesting. For 25 years, it never had. Now, in the early 1980s, it did. The ozone measurements were all over the place. The researchers suspected that their instruments had gone haywire. They sent new ones to Antarctica, but the data came back the same. At first, it seemed random.

But when the researchers looked more closely, they realised there was a pattern to the unusually low readings, a pattern related to the seasons, a pattern that reactions with chlorine could plausibly explain. NASA's satellites had also picked up some surprisingly low readings over the Antarctic. So low, the computers had initially thrown them out as obvious anomalies. Now, it was clear that something was happening. There was still room to doubt why.

Was it really a chemical reaction caused by chlorofluracarbons? Or was it solar activities or wind? There was only one way to be sure. NASA rushed to put together a team of scientists and flew them to Antarctica. In charge of the mission was 30-year-old Dr. Susan Solomon, an atmospheric chemist. Solomon had never been to Antarctica before,

and she didn't have the right equipment. Her team had brought instruments to analyze light from the moon, but they hadn't had time to build a tracking device to focus the moon's rays. Instead, someone had to sit on the laboratory roof at night, holding a mirror at just the right angle. The first time Solomon took the roof shift, she squinted to direct the mirror's reflection,

found that her eye had frozen shut, but the results of the experiments pointed only in one direction. On October the 20th, 1986, journalists gathered in Washington, D.C. to hear Solomon relay her team's preliminary findings over a crackly satellite list, from Antarctica. We have not conclusively established the cause of the ozone hole.

However... Solomon was right. More experiments confirmed it. The world's leaders acted with commendable speed. In 1987, they agreed the Montreal Protocol to phase out CFCs. Sherwood Rowland and Mario Molina shared a Nobel Prize.

The end of the world was averted. By now, the impacts of leaded gasoline on human health were equally plain to see. Governments around the world were banning that, too, albeit more slowly. As for Thomas Midgley, well, with hindsight, Boss Kettering's eulogy sounds a little different. Midgely contributed so greatly to more pleasant and efficient living. So he did. Safe refrigerators, aerosols, smoothly running gas engines, pleasant and efficient, just deadly too.

70 years after Ketwing's eulogy, the new scientist looked back on Midgeley's life, memorably describing him as a one-man environmental disaster. Far from the epitome of industrial progress, he starts to look more like a by word for that phrase coined by the great sociologist Robert K. Merton, unanticipated consequences. And yet, unanticipated consequences isn't a phrase you hear much anymore.

It's given way to unintended consequences. Merton himself switched from using one phrase to the other. They might sound like synonyms, but they're not. A professor of political science, named Frank Dresvart, points out that this shift in language obscures a whole category of impacts, ones that you don't intend, but you might nonetheless anticipate. Think of a doctor prescribing a drug that often has side effects. She doesn't want you to suffer the side effects, but she does foresee the possibility, or at least she should. And she should

be honest about it too. We expect doctors to speak truthfully about risks and trade-offs. Other decision makers might not, when they stand to gain, while the risks fall on others. In cases like that, says Dejvart, we should be sceptical when someone apologises for unintended consequences. It can be an attempt to evade responsibility for harms they didn't intend, but should have foreseen. That CFCs would destroy the ozone layer was genuinely unanticipated. Until Mario Molina sat down with his pencil and paper and calculator, it simply hadn't occurred to anyone as a possibility. But when Thomas Midgley and Boss Kettering launched tetraethyl lead as a fuel additive to stop engine knock, the danger was all too predictable.

It had been known for centuries that lead was poisonous. America's foremost expert in lead was Dr Alice Hamilton. In 1925, she pleaded with US regulators not to allow Midgley and Kettering to put lead in gasoline. I am not one of those who believe that the use of this leaded gasoline can ever be made safe. No lead industry has ever, even under the strictest control, lost all its dangers. Where there is lead, some case of lead poisoning sooner or later develops, even under the strictest supervision.

There had already been ample evidence of the risk, at a plant making tetraethyl lead in New Jersey, five of the 49 workers had died. Most of the rest had been taken to hospital in straitjackets, hallucinating, screaming and convulsing. Midgley and Kettering said that they could make the factories safe for workers. Even if that were true, said Alice Hamilton, you'd still have millions of cars belching lead in exhaust fumes into the air we all breathe. You may control conditions within a factory, but how are you going to control the whole country? Midgley insisted there'd be too little lead in exhaust fumes to cause any problems for human health. He didn't intend to poison people, but he should have anticipated that he might.

Alice Hamilton did, and she warned him. Faced with this kind of criticism, Boss Kettering knew that he needed to get public opinion on, on his side. Fortunately for him, Thomas Midley wasn't just an inventor, remember? He was that consummate showman we heard about earlier, filling his lungs with dichloro-difluoromethane to blow out a candle. At a press conference on leaded gasoline, Midley put on a similar kind of show. He produced a container of tetraethyl lead, poured the liquid all over his hands, and ostentatiously breathed in the fumes. I'm not taking any chance whatever,

nor would I take any chance doing that every day. The journalists were wowed. But Midgley must have known how disingenuous he was being, and how reckless. He'd just taken months off work to recover from lead poisoning himself. Kettering and Midgley knew the risks. Was there really no alternative? Well, when governments finally banned leaded gasoline,

scientists found different ways to prevent engine knock. When governments banned CFCs, scientists found alternative ways to make fridges, and air conditioners, and aerosols. Science is great. Midgely and Kettering knew of at least one promising potential alternative, ethyl alcohol. But any old farmer could make ethile alcohol from grain, whereas tetraethyl lead, was something that could be patented and monetized.

They just had to get past experts such as Alice Hamilton first. Midgely went to work on the job of introducing the new product to the public, an endeavor which he met with and finally overcame many obstacles and much opposition. Overcoming obstacles in opposition. It's a fitting line for a eulogy. But I can't help thinking of another fine phrase. The sociologist Robert K. Merton. The imperious immediacy of interest. Leaded gasoline would make a lot of money.

Who really cared what might happen next. For a full list of our sources, please see the show notes at timharford.com. Cautionary Tales is written by me, Tim Harford. with Andrew Wright. It's produced by Ryan Dilley with support from Courtney Garino and Emily Vaughn. The sound design and original music is the work of Pascal Wise. It features the voice talents of Ben Crow, Melanie Guthridge, Stella Harford and Rufus Wright. The show also wouldn't have been possible without the work of Mia LaBelle, Jacob Weisberg, Heather Fane, John Schnars,

Julia Barton, Carly MacLeory, Eric Sandler, Royston Berserve, Maggie Taylor, Nicole Morano, Daniela Khan, and Maya Koenig. Cautionary Tales is a production of Pushkin Industries. If you like the show, please remember to share, rate, and review, tell a friend, tell two friends. And if you want to hear the show ads free and listen to four exclusive Cautionary Tales shorts, then sign up for Pushkin Plus on the show page in Apple Podcasts or at pushkin.fm slash plus. This is an IHeart podcast. Guaranteed human.