Environmental Deposition of Trifluoroacetic Acid Due To Long‐Lived CFC Replacements and Anaesthetics
Generation and deposition of trifluoroacetic acid (TFA) is the subject of several recent papers. TFA is a PFAS in the scope of the universal PFAS restriction. The February 2026 Hart et al. paper “Growth in Production and Environmental Deposition of Trifluoroacetic Acid Due To Long‐Lived CFC Replacements and Anesthetics” [1] uses a chemical transport model to examine the global TFA budget arising from CFC replacements–hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs) and inhalation anaesthetics. Global TFA deposition from these sources increased ∼3.5‐fold from 6.8 (5.9–7.6) Gg/yr in 2000 to 21.8 (18.6 - 25.0) Gg/yr in 2022, with cumulative deposition reaching 335.5 Gg [1 Gg =1000 tonnes]. The paper reports that deposition is highest in the tropics and midlatitudes, and lowest in polar regions with deposition at the poles being considerably lower than global average TFA production and deposition. The paper reports that HCFC-123, HCFC-124, and HFC-134a account for most modelled TFA production and that long-lived CFC replacements account for virtually all of the observed Arctic deposition trend. At lower latitudes, their analysis supports the recent emergence of hydrofluoroolefins (HFOs) as a TFA source. The paper concludes that increased TFA monitoring is required.
The atmospheric model included three HCFCs (123, 124, 133a), six HFCs (134a, 227ea, 143a, 245fa, 365mfc, 43‐10mee), and four anaesthetics (halothane, isoflurane, desflurane and sevoflurane). Lifetimes of the TFA source gases were modelled and molar TFA yields were calculated. Molar yields of TFA were comparable to reported literature values, although with some important differences for some substances. For example, for HFC-134a the TFA yield was calculated to be 9%, which is at the low end of the reported range 7% to 20%.
Hart et al. report that the HCFCs (123, 124, 133a) provide an important, but declining, TFA source (∼68% of total TFA production in 2000; 19% in 2022 from these sources). Notably, high emissions of HFC-134a have led to it becoming the dominant TFA source in their study (∼28% of TFA production in 2000; 69% in 2022), despite its relatively low TFA yield (9%). For 2020, they estimate TFA production from HFC- 134a at 13.8 Gg, which is within the estimated 10–30 Gg range for 2020 reported in Scientific Assessment of Ozone Depletion 2022 [2]. Although relatively minor, the other HFCs considered (HFC‐143a, HFC‐227ea, HFC‐245fa, HFC‐365mfc, and HFC‐4310mee) and anaesthetics collectively accounted for 3.7 Gg (17%) of TFA production in 2022 and, according to the authors, their cumulative effects warrant consideration. Several other HFCs are also known TFA sources but were not included due to either insufficient observations with which to constrain the model or very low rates of TFA formation.
The authors explain the importance of using a full chemistry mechanism to explicitly calculate pressure and temperature dependent TFA yields, compared to a simpler model using prescribed yields based on laboratory studies, which on average showed a 14% larger TFA production rate. The authors reported the global atmospheric lifetime of TFA as 2 days, which means that deposition patterns closely follow TFA production, both spatially and temporally. Deposition fluxes demonstrate clear seasonal cycles, reflecting seasonality in TFA production (from OH‐initiated oxidation of precursors), and precipitation rates.
Explanatory Notes
1) The TFA production reported by Hart et al. for these substances uses a full chemistry atmospheric model, revised modelled lifetimes for the substances which will affect the annual TFA generation rate, and revised modelled TFA molar yields. Therefore, the overall TFA production would be expected to be potentially different to other estimates using different methodologies.
2) Although there are differences in the spatial distribution of TFA deposition from the long-lived F-gases, they are deposited globally due to their atmospheric lifetimes, with a large proportion being directly deposited in the oceans as the oceans cover about 71% of the earths surface.
3) Measured TFA concentrations suggest the Atlantic Ocean contains at least 40 million tonnes of TFA, possibly over 80 million tonnes. Anthropogenic emissions have been concluded to be responsible for only a small fraction of the TFA observed in the Atlantic Ocean, which must therefore include a large natural burden [3].
4) The UNEP Environmental Effects Assessment Panel, in their 2024 update, reviewed the risks of TFA to ecosystems and human health noting that “concentrations of TFA pose a de minimis risk in aquatic ecosystems” and “In conclusion, the risk to humans from chronic exposures to TFA in surface waters remains de minimis at current concentrations of TFA [4].
References
[1] Hart, L., Hossaini, R., Wild, O., Mazzeo, A., Halsall, C., Hou, X., et al. Growth in Production and Environmental Deposition of Trifluoroacetic Acid Due To Long‐Lived CFC Replacements and Anesthetics, Geophysical Research Letters, 2026, https://doi.org/10.1029/2025GL119216
[2] World Meteorological Organization (WMO), 2022, Scientific Assessment of Ozone Depletion: 2022, GAW Report No. 278; WMO: Geneva, 2022. Chapter 7: Scenarios and information for policymakers.
[3] Lindley, A. A., An Updated Inventory of Fluorspar CaF2 Production, Industrial Use, and Emissions of Trifluoroacetic Acid (TFA) from 1930, Including the Period from 2000 to 2020, Journal of Geoscience and Environment Protection, 2025, 13, https://doi.org/10.4236/gep.2025.1311008
[4] United Nations Environment Programme (UNEP), Environmental consequences of interacting effects of changes in stratospheric ozone, ultraviolet radiation and climate: UNEP Environmental Effects Assessment Panel, Update 2024, UNEP: This document is available online at the following location: https://ozone.unep.org/sites/default/files/2025-03/EEAP%20Update%20Assessment%202024.pdf