Scientists mean well. Of course I can’t speak for everyone, but most of us want to do good–good for science, good for humanity, good for the environment. Thomas Midgley, Jr., an especially prolific inventor with over a hundred patents, wanted to prevent the impending fuel crisis following World War I. While he achieved his goal which led to more powerful engines–an advantage in World War II–he also caused more irrevocable environmental damage than any other person in history.

Knock–that worrisome metallic ping! your car makes when accelerating hard in hot weather–was thought to come from a flaw in the design of internal combustion engines. Without knowing how to prevent knock, advancement had plateaued. No one could make the powerful, fuel-efficient engine America needed. Midgley, ever the innovator, soon discovered that knock actually came from a problem with the fuel, not the engine. Working for General Motors, Midgley led a trial-and-error search for an additive to prevent knocking.

The solution was to add a small amount of tetraethyl lead to current gasoline. The product was quickly put on the market and advertised as a superior alternative to ethanol-blended fuels–coincidently, ethanol-blended fuels were much more expensive for General Motors to produce. A year after the discovery, the American Chemical Society recognized Midgley’s work with the Nichols Medal–an 18 carat gold representation of “outstanding achievement in chemical research”.

General Motors along with the company now known as ExxonMobil formed the Ethyl Gasoline Corporation to mass-produce their new fuel additive. Not two months after the opening of the first tetraethyl lead chemical plant, five workers died and many others suffered from lead poisoning, hallucinations and insanity. To curtail the public backlash, Midgley participated in a press conference where he demonstrated the “safety” of tetraethyl lead by deeply inhaling its vapors for a full minute. Soon after he contracted lead poisoning, and sought treatment in Europe.

Although doping started in the 1920s, leaded gasoline remained the standard for many decades. It wasn’t until the 1970s with a study by Philip J. Landrigan where the dangers of lead additives were fully exposed. Landrigan, a pediatrician, tested the blood of children living near a smelting plant in El Paso, Texas. Sixty percent of the children were found to have elevated levels of lead in their blood. The public outrage forced the government to head Landrigan’s warnings and phase out the use of lead additives for more environmentally-friendly alternatives.

If inciting millions of motorists to shoot flumes of poisonous vapor into the air for close to fifty years isn’t enough damage for you, let’s look at Midgley’s other famous invention: Freon. Again Midgley meant well, at the time–again in the 20s–air conditioning and refrigeration units cooled their systems with flammable, toxic reagents such as ammonia and propane. Still with General Motors, Midgley was tasked to find a safe alternative. A good refrigerant must be volatile and chemically inert, and halogenated hydrocarbons were the obvious choice. He settled on dichlorofluoromethane, a small molecule with three halogens–a fluorine and two chlorines–bound to a carbon center. This compound, commonly called Freon 21, and similar chlorofluorocarbons refrigerants were, like leaded-gasoline, a huge success. They quickly became widespread in not only air conditioning and refrigeration but also in aerosol sprays–maybe you recognize the abbreviation for chlorofluorocarbon: CFC.

CFCs were standard in military aircraft as fire extinguishers beginning in World War II and transfered over to civil aircraft soon after. By the 1960s, these dry, powerless extinguishers were prevalent in computer rooms, laboratories, museums and anywhere with water-sensitive property. Along with refrigerant and propellant products, CFCs were everywhere.

At the peak of CFCs, an independent scientist, James Lovelock, fired up an electron capture detector–his own invention–and found fluorinated compounds in 50 separate air samples. Soon after, Mario J. Molina and his professor F. Sherwood Rowland discovered CFCs in the upper atmosphere are destroyed by solar radiation, creating chlorine radicals that destroy the ozone layer. Instead of burying this research in academic journals, the pair warned news media and politicians of the environmental damage done by CFCs. Regulation of these materials started in the 1990s, and by 2007 two hundred countries had agreed to eliminate CFCs entirely. Molina and Rowland, along with Paul J. Crutzen, won the 1995 Nobel Prize for Chemistry for their discovery of the destructive properties of CFCs.

So where is Thomas Midgley now? How does he feel knowing he created two of the most environmentally-damaging, mass-produced products to date? In 1940, Midgley contracted polio and was left unable to walk. He invented a system of string and pulleys to lift him out of bed, but in 1944 at the age of 55 Midgley was caught in his own device and strangled to death. He never knew the harm his inventions caused, which is probably for the best.