Chemicals designed to protect the ozone layer are now responsible for spreading massive amounts of a persistent forever chemical across the planet. A new study reveals that refrigerants and anesthetics introduced to replace ozone-damaging CFCs have led to over 335,000 tonnes of trifluoroacetic acid being deposited on Earth’s surface between 2000 and 2022.
Researchers at Lancaster University led an international team that used chemical transport modeling to calculate for the first time how much of this pollution has accumulated worldwide. The findings, published in Geophysical Research Letters, show that hydrochlorofluorocarbons and hydrofluorocarbons used in refrigeration systems, along with certain inhalation anesthetics, are the dominant atmospheric sources of trifluoroacetic acid.
Pollution Levels Continue Rising Despite Phase-Outs
Even though these F-gases are being phased out under the Montreal Protocol and the Kigali Amendment, their concentrations in the atmosphere are still increasing. Many of these CFC replacement chemicals remain airborne for decades, meaning trifluoroacetic acid will continue entering the environment long after the original emissions. Scientists estimate that annual production of the chemical from these sources could peak anywhere between 2025 and 2100.
Trifluoroacetic acid belongs to the per- and polyfluorinated alkyl substances family, a group of man-made chemicals known as forever chemicals because they resist natural breakdown and persist in the environment indefinitely. The chemical forms when specific gases break down in the air, then settles on land, water, and ice through rainfall or direct atmospheric deposition.
Arctic Ice Reveals Global Reach
The modeling demonstrates that nearly all trifluoroacetic acid detected in the Arctic originates from CFC replacement chemicals, even though the region sits far from major emission sources. Lucy Hart, a doctoral researcher at Lancaster University and lead author of the study, explained that CFC replacements have long lifetimes and travel through the atmosphere from their emission points to remote regions where they break down to form the chemical. Studies have found increasing levels in remote Arctic ice-cores, and the new results provide the first conclusive evidence that virtually all of these deposits can be explained by these gases.
To validate their findings, researchers compared their modeled estimates with real-world measurements from Arctic ice-cores and rainwater samples collected globally. They fed their model information on source gas quantities and locations using data from a global monitoring network, then simulated how these gases react with atmospheric components and break down to produce trifluoroacetic acid.
Health and Environmental Concerns Growing
The scientific understanding of trifluoroacetic acid’s effects is still developing. The European Chemicals Agency classifies the chemical as harmful to aquatic life. It has been detected in human blood and urine, and the German Federal Office for Chemicals recently proposed classifying it as potentially toxic to human reproduction.
While some regulatory agencies say current environmental levels fall below thresholds expected to harm people, concern is mounting about its steady and potentially irreversible accumulation. This has prompted calls for trifluoroacetic acid to be designated as a planetary boundary threat.
Next-Generation Refrigerants Add Uncertainty
Beyond polar regions, the modeling reveals another emerging source of concern. At midlatitude locations, evidence suggests that HFO-1234yf, commonly used in car air conditioning systems, is becoming an important and likely expanding source of atmospheric trifluoroacetic acid. Professor Ryan Hossaini of Lancaster University, a co-author of the study, noted that HFOs are marketed as climate-friendly alternatives to HFCs, but several are known to form the chemical. The growing use of these compounds for car air conditioning in Europe and elsewhere adds uncertainty to future environmental levels.
Professor Cris Halsall, Director of the Lancaster Environment Centre and co-author, pointed out that trifluoroacetic acid has generally been viewed as a breakdown product from fluorinated pesticides. However, it’s now clear that this very persistent chemical arises from the use and breakdown of a very wide group of organofluorine chemicals including refrigerants, solvents, pharmaceuticals, and the PFAS group in general.
Urgent Calls for International Action
Hart emphasized that the study highlights the broader risks that need to be considered by regulation when substituting harmful chemicals such as ozone-depleting CFCs. Professor Hossaini stressed the need to address environmental pollution because it is widespread, highly persistent, and levels are increasing. Although HFC use is gradually being phased down, this source will remain for decades. He called for a concerted international effort, including more extensive monitoring in the UK and elsewhere, to understand other sources and assess environmental impacts.
Dr. Stefan Reimann, whose research team in Switzerland monitors TFA-forming F-gases, said a consistent picture of increasing atmospheric concentrations and deposition to Earth’s surface is emerging in all regions where measurements are available. He noted that with increasing use of HFOs, accumulation in water bodies will potentially grow, making long-term monitoring a necessity.
