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White paper · May 2026 · In collaboration with ATMOsphere
Hanon Systems built a fleet-level model of trifluoroacetic acid (TFA) emissions from Europe's passenger cars. The finding: the switch to R1234yf cut global-warming potential but multiplied TFA generation, and without timely action the EU fleet could add up to 240,000 tonnes of this persistent “forever chemical” over the next 30 years.
ATMOsphere webinar · A conversation with Hanon Systems
Hanon Systems engineers walk the audience through the fleet-level model, the regulatory scenarios, and the PFAS-free alternatives: R744 (CO₂), already in series production, and R290 (propane), currently under development.
The Hanon Systems engineers behind the model, in conversation with ATMOsphere.
Speaker
Global Chief Engineer for Natural Refrigerant Systems
Hanon Systems
Speaker
Natural Refrigerant Systems Development Engineer
Hanon Systems
Host
Chief Executive Officer
ATMOsphere
Host
Editor at large
NaturalRefrigerants.com
TFA is a breakdown product of the refrigerant itself. Once R1234yf leaks from a car's air-conditioning or thermal management system, it reacts with hydroxyl radicals in the atmosphere, a process fuelled by sunlight, converting almost entirely to trifluoroacetic acid within days. TFA is so stable it effectively never leaves the water cycle.
The pathway · 4 stages
Vehicle air-conditioning leaks the refrigerants R1234yf and R134a into the atmosphere.
SourceR1234yf · R134a
Hydroxyl radicals, driven by sunlight, break the refrigerant down almost entirely into TFA.
Timescale~10 days
Trifluoroacetic acid: a persistent, highly water-soluble "forever chemical" that does not degrade.
Conversion~100% yield
Rain carries TFA into groundwater, crops and drinking water. It never leaves the water cycle.
PersistenceIndefinite
R1234yf converts to TFA at near-100% yield; R134a contributes too. TFA is highly water-soluble and environmentally persistent. It has been measured in European rainwater, tree needles, wine and human blood (white paper §3-4).
The regulatory path Europe chooses changes the TFA burden dramatically. Toggle between scenarios to see annual emissions from the EU passenger-car fleet, and how much TFA each option would avoid.
Cumulative 30-year figures (2028-2058) are from the Hanon Systems white paper, §3.3. Annual bar values are illustrative reconstructions of the published curve shapes, see the report for the full model.
TFA contamination from fluorinated gases used in mobile air-conditioning systems and already available PFAS-free alternatives. Authored by Hanon Systems, the chemistry of TFA formation, the fleet model, the regulatory scenarios, and the PFAS-free systems (R744 and R290) already in production.
TFA is a persistent, highly water-soluble breakdown product, a "forever chemical", formed when fluorinated refrigerants degrade in the atmosphere. It is environmentally stable and has been measured in European rainwater, tree needles, wine and human blood.
Yes. Once R1234yf (HFO-1234yf) leaks from a car's air-conditioning, it is oxidised in the atmosphere by hydroxyl radicals, a process fuelled by sunlight, and converts to TFA at near-100% yield within about 10 days. It produces roughly 5× more TFA per unit leaked than R134a.
Hanon Systems' fleet model projects up to 240,000 tonnes of additional TFA from the EU passenger-car fleet over 30 years with no further regulation, about 143,000 t under the ECHA proposal with derogations, and about 102,000 t under a strict ban. Around 68,000 t has already been emitted to 2026.
Natural refrigerants that produce no TFA: R744 (CO₂), already in series production with more than 1.3 million vehicles running PFAS-free CO₂ systems, and R290 (propane), currently under development.
Questions about the model, the data, or the alternatives? Get in touch with the Hanon Systems team.