A chemical is building up in rainwater, glaciers and drinking water across the globe. The compounds responsible are known for protecting the ozone layer.
Researchers at Lancaster University have found that refrigerants and anesthetics used as replacements for ozone-harming chemicals have deposited roughly 335,500 tonnes of a compound called trifluoroacetic acid onto Earth’s surface between 2000 and 2022. This trend shows no signs of slowing down at all.
TFA is formed when modern refrigerants and gases, widely used in air conditioners, refrigerators and hospital equipment, break down in the atmosphere. When refrigerants and gases are released into the air, sunlight and atmospheric reactions slowly oxidize them. Over time, that interaction transforms them into TFA.
TFA belongs to a class of substances known as PFAS or per- and polyfluorinated alkyl substances, more commonly known as “forever chemicals” because their strong carbon-fluorine molecular bonds make them extremely resistant to natural breakdown processes. Unlike many pollutants that degrade over time, TFA remains chemically stable, allowing it to accumulate in soil, rivers and ice long after it first falls with rain.
When scientists in the 1980s discovered that chlorofluorocarbons — the chemicals used in older refrigerators and aerosols — were destroying the ozone layer, the world took action. The Montreal Protocol of 1987 led to a global phase-out of those compounds and their replacement with hydrochlorofluorocarbons and hydrofluorocarbons.
The Lancaster team used chemical transport modeling, validated against data from Arctic ice cores and rainwater samples, to trace exactly where TFA lands. The findings, published in Geophysical Research Letters reported in ScienceDaily, showed that virtually all TFA detected in the Arctic can be traced back to those CFC replacement chemicals, despite the Arctic sitting far from any major emission source.
Lucy Hart, a researcher at Lancaster University and the study’s lead author, said “CFC replacements have long lifetimes and are able to be transported in the atmosphere from their point of emission to remote regions such as the Arctic where they can break down to form TFA.”
The problem will not resolve itself once these gases are phased out. However, HCFCs and HFCs already in the atmosphere will continue generating TFA for decades. Scientists estimate that peak annual TFA production could reach its highest levels anywhere between 2025 and 2100. A newer class of refrigerants known as HFOs, common in car air conditioning and marketed as climate-friendly, are also known TFA-forming compounds.
“The growing use of these chemicals for car air conditioning in Europe and elsewhere adds uncertainty to future levels of TFA in our environment,” professor and study co-author Ryan Hossaini, told in a press release.
Regulators are beginning to take action. The European Chemicals Agency listed TFA as harmful to aquatic life and Germany’s Federal Office for Chemicals has proposed classifying it as potentially toxic to human reproduction. TFA has also been detected in human blood and urine, though whether it poses a direct risk remains an open question.
The ozone layer is healing, but the chemicals used to save it are leaving a quieter and much more invisible legacy. “This really highlights the broader risks that need to be considered by regulation when substituting harmful chemicals,” Hart said.
