So who is the most dangerous disabled person in history? Who could possibly beat Kaiser Wilhelm and Joseph Goebbels? Well, the man's name is Thomas Midgley. Never heard of him? Then let me enlighten you. In the first half of the 20th century Midgley was one of America's leading scientists and inventors, receiving virtually every major prize in chemistry. However, his life wasn't all plain sailing. Unusually, in middle age he contracted polio which left him paralysed from the waist down. Applying his scientific mind to the situation, Midgley calculated that the probability of this happening was "equal to the chances of drawing a certain individual card from a stack of playing cards as high as the Empire State Building".
Midgley is famous, or perhaps I should say notorious, for two achievements. While working in the research department of General Motors he resolved to find a way of making petrol burn more evenly and thus improve the efficiency of cars. He was keen to stop the irritating knocking sound caused by uneven combustion in engines. For month after month he experimented with everything "from melted butter...to aluminium chloride".
Eventually, in 1921, he made the breakthrough he had been looking for. He discovered that adding lead to petrol solved the problem. Two years later leaded petrol went on sale for the first time and it soon became the norm worldwide.
Sadly, what Midgley didn't appreciate was that lead in petrol posed a major threat to human health. As people inhaled car exhaust fumes, lead could build up in their bodies, causing serious diseases and impairing brain function. Children were particularly vulnerable. Decades after Midgley first recommended putting lead in petrol, it was banned to protect people's health.
The next challenge Midgley set himself was to devise a more effective method of refrigeration. In the 1920s, mechanical refrigeration was still a relatively new piece of technology, but it was beginning to transform people's lives. Suddenly it became possible to air condition buildings and keep food edible for longer. Domestic fridges were incredibly popular and by 1929 Frigidaire had sold one million to households around America.
However, there was a major drawback to the chemicals used inside these fridges. Every known refrigerant material was either poisonous or flammable or both. This didn't matter as long as the chemicals remained inside their pipes, but inevitably leaks occurred, sometimes with fatal results. Midgley's goal was to find a substance that would avoid these risks. After an intensive series of experiments, Midgley came up with a new compound which tests showed was completely inert, non-flammable and non-toxic. It did the job it was supposed to do and seemed perfectly safe. Midgley called the chemical Freon. Today we know its family of chemicals as chlorofluorocarbons or CFCs.
It wasn't long before Freon was being installed in fridges throughout the world. Later other uses for it were found as well. During World War II, the US Department of Agriculture discovered that Freon made an excellent propellant and used it to spray insecticide in Asian jungles where soldiers were succumbing to insect-borne diseases. This gave rise to aerosol spray cans which soon became a common consumer product. Manufacturers also came to realise that Freon was ideal for making foam rubber for furniture.
Unfortunately, CFCs turned out to be disastrous. In the 1970s it was discovered that CFCs were accumulating in the upper reaches of the atmosphere and destroying the crucial ozone layer which protects the Earth from the Sun's harmful ultraviolet rays. If the ozone layer didn't intercept these rays, they would not only weaken the human immune system and cause cancer but also kill off algae on which the ocean food chain depends. Without an ozone layer, life as we know it would simply not be possible.
As the years went by, scientists gradually realised how serious the situation was. By 1983 researchers at the British Antarctic Survey and NASA were detecting a hole the size of the United States in the ozone layer over Antarctica. Some springs the level of ozone in the Antarctic atmosphere was plummeting to less than half of what it should be. One academic calculated that a single chlorine atom from CFCs could destroy 100,000 molecules of ozone.
In 1987, 21 countries and the European Union signed the groundbreaking Montréal Protocol, the first ever international agreement to cut emissions of a polluting chemical. This fixed a target of reducing CFC production by 50 per cent by 2000. The following year, new research showed that the ozone layer was damaged in the northern hemisphere as well. Finally, in 1996 CFC production and use was banned altogether. Even so, Midgley's chemical will stay in the atmosphere for the rest of the 21st century. Each one of us inhales CFCs in every breath we take.
Despite everything, I can't help feeling some pity for Midgley. He was incredibly unlucky. Not only did he unwittingly devise one of the most environmentally hazardous materials ever known, he also met the most ignominious end. Always inventing things, he designed a hoist to lift him out of bed. Unfortunately, one morning in 1944 the pulley's ropes became tangled around his neck and he was strangled to death.
And perhaps it is unfair of me to include him in the same list as Kaiser Wilhelm and Goebbels. After all, his only aim was to improve the lives of human beings by making technology work better. He didn't act out of malice, greed or prejudice. Nevertheless, the outcome of his work was - by any definition - highly dangerous.
As the science writer Gabrielle Walker observes, Midgley was "inadvertently responsible for more damage to Earth's atmosphere than any other single organism that has ever lived". The hole in the Antarctic ozone layer will continue to appear every year throughout the 21st century. Indeed, the hole is likely to grow worse before it becomes smaller. As the saying goes, the road to hell is paved with good intentions. Unless you're a wheelchair user of course, in which case the road to hell is paved with cobblestones.