TFA Generation and Deposition over Europe May Currently See a Greater Influence from HFO-1234yf than HFC-134a

Concerns around the prevalence of trifluoroacetic acid (TFA, CF₃COOH) in the environment have been ongoing for more than 20 years. One source of TFA to the environment is via the atmospheric degradation of fluorinated gases (F-gases) to TFA and its subsequent deposition. During the past decade, controls on one major class of F-gases, hydrofluorocarbons (HFCs), have resulted in an increase in the production and use of hydrofluoroolefins (HFOs). Here, a tropospheric chemical transport model, STOCHEM-CRI, is used to compare the amount of TFA generated by the breakdown of an abundant HFC, HFC-134a (1,1,1,2-tetrafluoroethane, CF₃CH₂F), and its typical replacement, HFO-1234yf (2,3,3,3-tetrafluoropropene, CH₂CFCF₃). Using derived global emission estimates for 2023, we predict that HFO-1234yf is already dominating atmospheric generation and deposition of TFA over Europe when compared with HFC-134a. This is despite the fact that the derived global emissions of HFC-134a are 22 times higher than those of HFO-1234yf. Globally, our simulations show that TFA production from HFO-1234yf is already equivalent to 26-75% of the TFA production from HFC-134a. As the transition away from HFCs progresses, it is likely that HFO-1234yf will continue to increase in its global contribution to TFA generation and resultant environmental contamination.