A new study reveals that chemicals introduced to protect the ozone layer are now contributing to widespread deposition of trifluoroacetic acid, a persistent forever chemical, across the planet. Researchers estimate that 335,500 tonnes of this pollutant have accumulated on Earth's surface from 2000 to 2022. Even as these substances are phased out, their long atmospheric lifetimes mean pollution levels will continue rising for decades.
Chemicals developed to replace ozone-depleting chlorofluorocarbons (CFCs) are unexpectedly fueling the spread of trifluoroacetic acid (TFA), a member of the per- and polyfluorinated alkyl substances (PFAS) family known as forever chemicals for their resistance to breakdown. A team led by researchers at Lancaster University used chemical transport modeling to quantify this pollution for the first time. Their analysis, published in Geophysical Research Letters, shows that hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and certain anesthetic gases have led to the atmospheric deposition of roughly 335,500 tonnes of TFA between 2000 and 2022.
These F-gases, widely used in refrigeration and air conditioning, break down in the atmosphere to form TFA, which then rains out or settles onto land, water, and ice worldwide. The study highlights that pollution is not yet at its peak: annual TFA production from these sources could reach maximum levels between 2025 and 2100 due to the gases' decades-long persistence in the air. In remote areas like the Arctic, nearly all detected TFA originates from these CFC replacements, as confirmed by ice-core data and rainwater samples.
Environmental concerns are mounting. The European Chemicals Agency deems TFA harmful to aquatic life, while it has been found in human blood and urine. Germany's Federal Office for Chemicals recently proposed classifying it as potentially toxic to reproduction. Although current levels are below known human health thresholds, experts warn of irreversible buildup.
"Our study shows that CFC replacements are likely to be the dominant atmospheric source of TFA," said lead author Lucy Hart, a PhD researcher at Lancaster University. "This really highlights the broader risks that need to be considered by regulation when substituting harmful chemicals such as ozone-depleting CFCs."
Emerging refrigerants like HFO-1234yf, used in car air conditioning, are adding to future uncertainties. "HFOs are the latest class of synthetic refrigerants marketed as climate-friendly alternatives to HFCs," noted co-author Professor Ryan Hossaini. "A number of HFOs are known to be TFA-forming and the growing use of these chemicals... adds uncertainty to future levels of TFA in our environment."
The researchers, including collaborators from institutions in the UK, Australia, Norway, the US, Switzerland, and South Korea, call for urgent international monitoring and assessment of TFA's impacts under frameworks like the Montreal Protocol and Kigali Amendment.
