Forever Chemical Rain from CFC Replacements Coats Earth

Scientists have found that chemicals brought in to fix the ozone hole are now dropping a stubborn pollutant called trifluoroacetic acid, or TFA, across the entire planet. This invisible rain has coated water, land, and ice with 335,500 tonnes of TFA between 2000 and 2022, including spots as far away as the Arctic. The main culprits are gases used to replace chlorofluorocarbons, or CFCs, plus some medical anesthetics. Even though older chemicals are being pulled back, TFA levels are still climbing because these gases hang in the air for decades before breaking down into TFA.

Background

Back in the 1980s, the world spotted a hole in the ozone layer high up in the sky. That layer blocks harmful sun rays, so countries agreed to stop using CFCs, which were eating it away. Factories switched to new gases called hydrofluorocarbons, or HFCs, and other fluorinated gases. These helped the ozone recover, but they had a side effect no one saw coming at first.

These replacement gases break down slowly in the atmosphere. When they do, they turn into TFA, a simple acid that does not break down further. It sticks around forever, which is why experts call it a forever chemical. Rain and wind carry it down to Earth, where it soaks into rivers, lakes, soil, and even builds up in plants and ice.

Researchers at Lancaster University in the UK led a team that measured this for the first time. They looked at air samples, water tests, and ice cores from places like the Arctic and remote mountains. What they saw was TFA everywhere, even where no factories operate nearby. The numbers show deposits jumped from about 6,800 tonnes a year in 2000 to much higher now.

TFA comes from more than just CFC replacements. Pesticides with PFAS, drugs, and factory runoff add to it. In Europe, regulators noted groundwater problems with TFA as far back as 1998. It shows up in nearly every water body tested, and standard filters at water plants do not catch it.

Key Details

The Lancaster team calculated that HFCs and similar gases made up the biggest share of TFA fallout over those 22 years. Anesthetics used in hospitals also contribute a smaller but steady amount. These gases can stay aloft for 20 to 100 years, so TFA will keep falling even as HFC use drops under new climate rules.

Spread and Buildup

TFA moves easily through air and water. Tests show it in Arctic ice, ocean water, and high mountain snow. Near factories in China, plants soak it up at high rates, with one study finding levels 13,000 times higher in leaves than in soil. It builds in tree needles, corn crops, and wetland plants.

In landfills and industrial zones, air and dust carry TFA at levels up to 9.5 nanograms per cubic meter. Leaves near these sites hold up to 48 micrograms per gram of fat. Groundwater often has it too, and it does not go away.

Soil tests show effects at high doses, like slower breakdown of plant litter when levels hit 10 milligrams per kilogram. That drop comes from the acid's low pH. Microbes in river mud take it into their cells, and it ends up in proteins across food chains.

Health and Safety Checks

Some agencies say current TFA levels in water and air stay below points thought to hurt people right now. But worry grows because it builds without stop. Plants and tiny river life show changes, and human exposure thresholds exist for drinking water as a precaution.

"Our study shows that CFC replacements are likely to be the dominant atmospheric source of TFA," said Lucy Hart, PhD researcher at Lancaster University and lead author of the study. "This really highlights the broader risks that need to be considered by regulation when substituting harmful chemicals such as ozone-depleting CFCs."

Professor Ryan Hossaini, who worked on the project, pointed to the long tail of this pollution.

"There is a need to address environmental TFA pollution because it is widespread, highly persistent, and levels are increasing," said Professor Hossaini. "The rising levels of TFA from F-gases is striking. Although HFC use is gradually being phased down, this TFA source will remain with us for decades."

What This Means

TFA fits what experts call a planetary boundary threat. That means it spreads worldwide, sticks around forever, and could tip key Earth processes out of balance without us knowing until too late. No one can clean it up easily once it lands.

Peak fallout from these gases might hit between 2025 and 2100. Annual amounts could jump tenfold in the next decade. That calls for better tracking in places like the UK and global checks on all sources, from farms to factories.

Rules now phase down HFCs to fight warming, which helps a bit. But other paths to TFA, like PFAS pesticides, keep feeding the problem. Groups push for broad bans on PFAS to cut new inputs and shift to safer options.

Plants pulling in TFA could change how forests and crops grow over time. River and lake life might shift, affecting fish and birds. In the air, high levels could tweak cloud seeds and particle formation, but more study is needed.

Governments eye research on how PFAS like TFA hit wildlife and whole ecosystems. Water plants test new ways to filter it, but for now, it flows through. The shift from CFCs saved the ozone but left this lasting mark, one that builds quietly year by year.