F for Forever

Fluorine (F), indeed, is an atom to which one should pay respects. It is the most electronegative element, meaning the bonds it forms are extremely strong. Fluorinated gases are strong greenhouse gases because their lifetimes are so long. Some last for thousands of years. The main use of many of these molecules is as coolants within air conditioners and refrigerators. Chemicals like CFCs and HCFCs were the substances that depleted the ozone layer. They also caused substantial global heating. Other fluorinated gases such as HFCs and PFCs have been used as replacements for their ozone-depleting counterparts, but still cause heating.

Fluorinated compounds wreak havoc in terrestrial settings as well. PFAS and PFOS are compounds like Teflon, which create tremendous profits for chemical companies but are potentially linked to health risks such as cancer, thyroid disease, and liver damage. These chemicals are extremely long-lived in the body, and are now inside nearly every human on Earth in measurable quantities. DuPont has paid hundreds of millions in settlements relating to health impacts linked to PFAS, and some of these stories were the subject of the documentary film The Devil We Know and the biopic Dark Waters.

History of forever chemicals

A Belgian chemist named Frédéric Swarts added carbon to fluorine and synthesized several brand-new fluorocarbon compounds. Chlorofluorocarbons, or CFCs, the substances that would ultimately punch a hole in the ozone layer, were first synthesized by Swarts in the 1890s. There are a couple dozen different types of CFCs, all synthetic molecules, which never existed on Earth before their invention.

Fluorine’s extremely reactive nature also means that it clings to other atoms tightly. The fluorine-carbon bond is stronger than any other element forms with carbon. This property, and the F-C atomic symbols, inspired the designation “forever chemical.” CFCs are non-corrosive and have a remarkably long lifetime even in the harshest environments. These are properties that make them very appealing for use in everyday products, such as refrigerators or spray cans. Their resilience also means they stay in the atmosphere for decades, which is a major reason why CFCs have such a destructive effect on our environment.

The use of CFCs in industry was popularized in the 1920s by an unfortunate chemist named Thomas Midgley, Jr. Midgley ended up leaving a toxic legacy through his popularization of two major environmental pollutants. While employed in the Frigidaire division of General Motors, he was tasked with finding a new chemical refrigerant, the substance that moves heat as it is compressed and expanded within the coils of a refrigerator. When Midgley first used CFCs as a refrigerant, they were lauded for their relative non-toxicity, non-flammability, and inertness. He used Swarts’ process to make the CFCs, and beautiful fluorite minerals were mined to provide the source of fluorine. The use of CFCs in air conditioners followed soon after, and the popularity of these new products led to massive increases of CFC synthesis during the mid-20th century.

Thomas Midgley and Leaded Gasoline

Ironically, Thomas Midgley, Jr. was also behind another major environmental disaster of the 20th century, leaded gasoline, and for this he deserves significant blame. Gasoline is unleaded in its natural state. Each gallon of leaded gasoline has a toxic substance called tetraethyl lead added to it to reduce the problem of engine knocking. Midgley first added lead to gasoline while working for a subsidiary of General Motors in the 1922. The risks of lead as a neurotoxin were well known at that time. Tetraethyl lead in particular had been studied as a chemical weapon.

Safe additives such as ethanol were identified quickly to prevent knocking. But any moonshiner can make ethanol, the substance that is more commonly known as drinking alcohol. Ethanol was rejected in favor of tetraethyl lead, which could be patented, making GM and its partner DuPont a profit on each gallon of leaded gas sold for decades into the future.

At this time of his invention, Midgley’s research division was struggling and losing money for the company, and he was desperate to create a profitable product. So he threw caution to the wind and pressed on with lead, even as workers in his factory began to hallucinate and go insane, reporting visions of butterflies within the factory. Midgley stood by as 19 workers in early lead factories were poisoned and died, vigorously fighting any public criticism. At a press conference following several worker deaths, Midgley poured lead over his hands to demonstrate its supposed safety, claiming he could do this every day without affecting his health. This was despite the fact that he himself had been recently stricken with lead poisoning, and had to abandon his work and recuperate in fresh air for several months. The deceptions that this man wove in order to protect profitability are stunning and despicable.

The aggressive public relations strategy continued and was highly successful for GM and their partners, as leaded gas was sold in the US for an incredible 50 more years, during which they made massive profits on the toxic additive. Following newfound attention to environmental concerns, the phase out of lead from gasoline started in the mid-1970s in the United States. The final nail in the coffin for lead in the U.S. came because catalytic converters, which are put on cars to reduce air pollution, cannot work effectively with leaded gasoline. Of course it was the environmental movement that pushed for these pollution controls on cars, so tree huggers deserve credit for the lead ban as well.

Many countries of the world were much slower with outlawing lead. Leaded gas was aggressively marketed to lower-wealth countries well into the 21st century. But nearly all nations have now eliminated lead from their fuel supply. The world has finally escaped from the shackles of lead, which poisoned our children for so long. More recent research has shown that exposure to even small amounts of lead is associated with lower IQ in children, increased aggression, and premature death.

Some have even suggested that the recent fall in violent crime rates, which began to drop approximately 20 years after the lead ban, has been due to reductions in environmental lead levels. Homicide rates in the United States fell by 50% between 1990 and 2010, and similar reductions have been detected in other countries, coming two decades after their lead bans. Since lead is known to affect the brain in ways that decrease IQ and reduce impulse control, it is probable that lead caused at least part of the decline in crime. It is stunning that for over half a century, we put substances into the environment that make people less peaceful and less intelligent. Scores of scientists warned of the risks of lead since its adoption in the 1920s, but no one with the power to stop it listened.

Midgley was part of a group of scientists and engineers who believed that technology would provide solutions for everything, and believed that tech entrepreneurs deserved carte blanche with their products. An address that he gave about the future of engineering is telling. Midgley was clearly livid about New Deal policies that supported farm workers when crops were failing. He suggested that technocrats could block out the sun in order to reduce crop yields everywhere until the government gave control back to oligarchs and stopped social welfare programs from interfering with progress.

Following the introduction of CFCs into refrigerators in the 1920s, CFC production increased astronomically throughout the 20th century. By the 1970s industry was producing thousands of times more of the gases than in the 1930s. In addition to their use in refrigerators and air conditioners, a large amount of CFCs went into spray can propellants, in products such as hairsprays, deodorants, and spray paint. The other primary uses were in foams and industrial chemicals. Since CFCs have been completely banned as propellants, you can now spike up that mohawk or puff out that bouffant without fear of ozone loss.

With the invention in the 1960s of instrumentation that could detect chemicals in miniscule quantities, pollutant levels of many compounds, including CFCs, were tracked worldwide. It was perhaps not so surprising to find CFCs in the air above polluted cities, but scientists detected them every single place they looked. CFCs were discovered in even the most remote areas where there is little sign of other pollutants like smog. CFCs are synthetic molecules with no natural sources, so even in these remote locations their presence was human-caused. The chemicals evidently had drifted many thousands of miles without being removed from the atmosphere. Measurements indicated that in fact much of the CFC gas that had been emitted historically, even from previous decades, was still in the atmosphere.

The potential for CFCs to destroy ozone was first discovered in 1974 through theoretical calculations done by Mario Molina and Sherwood Rowland, who would later win the Nobel Prize in Chemistry for their finding. The “chloro” part of the chlorofluorocarbon ends up being the key: when CFCs are hit by UV light, a highly reactive chlorine atom breaks off. This reacts with ozone, destroying it and creating oxygen and a new molecule, chlorine monoxide. That is not the end of the story though – the new molecule quickly reacts away, leaving only oxygen and the original chlorine atom. So after these two reactions, we are back to the start, except ozone has been eliminated. The original chlorine atom still exists and is just as reactive. These reactions can proceed over and over, destroying a massive amount of ozone, until the chlorine finally reacts away into a more stable compound. Each CFC molecule on average can destroy 100,000 ozone molecules before the cycle completes. Such destructiveness is hard to comprehend: imagine one bad apple spoiling the entire orchard.

Since each molecule of CFC can wipe out massive amounts of ozone, even household items like spray deodorants could cause severe damage. These were not chemicals that were being emitted en masse from smokestacks or from every vehicle’s tailpipe.  CFC emissions were small compared with the size of the ozone layer, so the scientific prediction was for a relatively gradual decrease in ozone of around 10% globally. With a 10% loss in ozone, it was estimated that there would be a 20-30% increase in skin cancer cases globally.

Despite the large potential health impacts of ozone depletion, government responses were generally rather weak. There were a few exceptions where environmental protection took precedence. Progressive U.S. states like Oregon led the way by passing CFC bans in aerosol sprays as early as May of 1975., and the country as a whole passed a similar law in 1978. This was followed by bans in Canada and three Scandinavian countries. CFCs continued to be produced in refrigerators, air conditioners, and other “essential” uses in these countries however. Other countries, including most of Europe, dragged their feet even on spray cans.

Industry groups used disinformation campaigns to try to cast doubt on the science and hinder regulations. A few scientific studies that suggested that ozone depletion might be less severe were highlighted by skeptics. Pro-CFC industry campaigns in the U.S. often made the argument that unless the rest of the world acted we should not be acting either. Of course, many of these techniques are very familiar to those observing industry propaganda about the climate crisis.

Painting by Virginia Wright-Frierson

CFCs and the Ozone Hole

The discovery of a hole in the ozone layer over Antarctica in 1985 came as one of the most surprising scientific findings of the century. The rapid ozone loss was discovered first by workers in Antarctica using ground-based measurements, and was soon after confirmed in satellite data.

Scientists arrived at the Halley Research Station in October of 1981 to make the same ozone measurements they had been performing since 1957. The team of Joseph Farman, Brian Gardiner, and Jonathan Shanklin from the British Antarctic Survey were lucky to have their ozone-measuring instrument still in place in Antarctica. Routine monitoring is too often seen as less valuable than a new measurement technique, and in times of fiscal stress, their prized long-term ozone measurements had barely escaped the chopping block. A superior once jested with Farman, “You’re making this measurement for posterity? What has posterity done for you?”

The observers performed their measurements as usual, but when they found such extreme low values, they assumed their equipment was malfunctioning. They had a new instrument sent over, calibrated directly against the standard, but the new measurements were identical. It was assumed for a while that changing weather conditions might explain the loss, and a backlog of data processing prevented the researchers from immediately recognizing the extent of the decline.

A key discovery was made when Shanklin prepared data for an open house in 1983, when the general public was invited to visit his lab in England. Often interactions with the public can shake scientists out of their ivory tower, and help them focus on problems that are more relevant to our everyday lives. In this case, Shanklin hoped to reassure the visitors that ozone loss was not happening very quickly. Instead the analysis he performed for this public outreach event set the ball in motion for one of the most significant scientific discoveries of the century. He found unprecedentedly low values of ozone occurring in the spring. He and his collaborators pored over the data for months, and ruled out more and more possible explanations. In the meantime, each subsequent year showed a larger and larger decline.

By the end of 1984, the researchers had enough confidence to share their results: a massive hole in the ozone layer was appearing over the station each year. The rapidity of its formation was amazing; concentrations were 40% lower than just nine years before. NASA scientists soon confirmed that satellite instruments could see the precipitous decline as well, and that the ozone hole was a similar size as the entire continent of Antarctica below, and larger than the areas of the US and Mexico combined. At its largest, the hole is wide enough for the Moon to pass through it.

Farman and his team pointed their finger at CFCs as the most likely cause of the ozone hole. Scientists raced down to Antarctica, attempting to determine whether the accusation could be confirmed or if natural factors might be at play. A team in Antarctica led by esteemed researcher Susan Solomon took measurements and developed a comprehensive understanding of the ozone hole, proving that our emissions of CFCs were the cause.

Calls for bans on CFCs from the public became urgent. Citizens demanded CFC-free replacements for any product containing ozone-depleting substances and were often successful with their pushes. A campaign started by elementary school students to get McDonald’s restaurants to stop using foam packaging made with CFCs was amplified by environmental groups and eventually culminated with the entire foam industry agreeing to remove CFCs from their products.

Governments responded soon after. The Montreal Protocol, an international treaty that scheduled the phase-out of CFCs, was initially signed in 1987 by 46 countries from all over the world. In the US Senate it was ratified with unanimous approval. In a dramatic showing of world solidarity, more and more nations from around the world signed on. After the treaty took effect in 1989, the use of CFCs quickly plummeted, and as a direct result of the agreement, CFC production has been almost completely eradicated from our planet. The Montreal Protocol is universally recognized as one of the most successful environmental treaties ever put into action. All 196 countries in the world, including those that did not even exist back in 1987, have signed it, making it the first treaty in the history of the United Nations with universal ratification. Former Secretary General of the United Nations Kofi Annan called it “perhaps the single most successful international agreement to date.”

In the decade following the Montreal Protocol, despite the sharp decline in CFC use, ozone depletion continued to get worse. This was expected because it takes years for CFCs to be transported into the stratosphere. Spray can emissions from the early 1980s were still making their way up to the ozone layer in the late 1990s. More recently the ozone hole has started to shrink, but since the chemicals are so persistent, even seventy years after the Montreal Protocol, echoes of the damage from CFCs will remain. Current predictions are for a closing of the ozone hole by around the year 2060. As with carbon dioxide, the pollution continues to impact the Earth long after steps are taken to correct the damage.

An unintended benefit of the Montreal Protocol is that substantial global warming has been prevented by the agreement. This is not because of the healing of the ozone layer itself, as the additional UV radiation that makes it through the ozone hole is negligible in heating the Earth. CFCs are also greenhouse gases that trap heat from escaping from our planet just like carbon dioxide and methane. Their warming effect is not negligible: CFCs have caused around 10% of the global warming as carbon dioxide, the number one cause of our planetary fever. In fact, the Montreal Protocol has been one of the most important single public policy decisions in reducing greenhouse gas emissions, which is ironic given that climate was not the focus of the treaty.

Some of the replacements for CFCs, called hydrofluorocarbons or HFCs, are strong greenhouse gases as well. Fluorine is ultimately at fault again, as the stable molecular bonds it forms create long-lasting gases which easy trap heat radiation from the Earth. Even though HFCs are only produced in relatively small quantities, we could make an important dent in heat-trapping gas emissions by outlawing these substances. Safe alternatives to HFCs and CFCs have existed for decades. Greenpeace helped develop an environmentally refrigerant called Greenfreeze in 1993, which has been used in hundreds of millions of refrigerators since then, preventing substantial global warming. It is in a minority of fridges worldwide though, so HFCs remain a large source of greenhouse gas emissions. Governments have made some progress in regulating HFCs under the same framework as ozone-depleting substances, taking advantage of the success of the ozone treaty to fight climate change.

The Montreal Protocol was a monumental success; clearly ozone depletion could have been much worse if we had delayed action. What if we were still wrangling over CFC bans, or even worse, if we had not noticed the problem at all?  Recent work has used careful calculations to quantify the damage that would have been done had we continued to emit more and more CFCs into the atmosphere through the 21st century. The environmental damage in such a scenario is staggering. By 2020 an ozone hole would have opened over the Arctic, exposing much more human population and land ecosystems to UV radiation. By 2065 a third ozone hole would open over the tropics, and we would have lost 2/3rds of the world’s ozone. The entire planet would have been affected: sunburns would begin after just 5 minutes, and skin cancer and cataract rates would soar. The impacts on ecosystems, crops, and other aspects of life on Earth from such a change in radiation are simply unknown because it is such a different world than today, but each would likely be affected quite negatively. Halting the production of these forever chemicals saved us from a tremendous amount of harm.

Let us also consider the opposite extreme. What if a strong policy response had been implemented right after the first ozone depletion theory was published? Since emissions were increasing exponentially before the ozone problem was discovered, around 2/3rds of the total CFC emissions in human history happened after the ozone link was first posited in 1974. In other words, the vast majority of the world’s CFC emissions happened after we had a good idea that they could be causing severe harm, twice as much as before we knew. What if we had taken action right away? If a program of similar scope to the Montreal Protocol had instead been implemented in 1976 instead of 1989, industry would have emitted 40% less CFCs over human history.


Science for the People is a radical organization of scientists founded in 1969 and relaunched in 2015. They publish a magazine and have chapters across the US and Mexico.



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