Climate-Friendly Refrigerants and Forever Chemicals: Why Replacement Technologies Need Environmental Testing

Climate-Friendly Refrigerants and Forever Chemicals: Why Replacement Technologies Need Environmental Testing

A refrigerant introduced to reduce the climate impact of vehicle air-conditioning systems may be creating a different environmental challenge.

HFO-1234yf has increasingly replaced HFC-134a in vehicle air conditioners because the older refrigerant is a potent greenhouse gas. HFO-1234yf has a much shorter atmospheric lifetime and a substantially lower direct global-warming impact, making it attractive as a climate-focused replacement. However, when released into the atmosphere and chemically degraded, it can form trifluoroacetic acid, commonly known as TFA.

TFA is highly persistent and mobile. It can be transported through atmospheric deposition and the water cycle and has been detected in environmental water, plants, food and human samples.

New University of Bristol-led research indicates that HFO-1234yf may already be contributing more to TFA deposition across parts of Europe than the older refrigerant it replaced—even though estimated global emissions of HFC-134a remain approximately 22 times higher.

The finding illustrates a wider environmental principle:

A replacement technology should not be assessed only by the environmental problem it solves. It must also be evaluated for the pollutants, transformation products and exposure pathways it may create.

Why HFC-134a was replaced

HFC-134a was widely used in mobile air-conditioning systems but has a high global-warming potential.

Efforts to reduce emissions of high-global-warming-potential refrigerants encouraged vehicle manufacturers to transition toward alternatives such as HFO-1234yf. The newer refrigerant breaks down much faster in the atmosphere and therefore has a lower direct climate impact.

HFO-1234yf is now used in almost all new cars manufactured globally since 2017, according to the University of Bristol release.

From a climate perspective, replacing a long-lived, powerful greenhouse gas with a shorter-lived alternative appears beneficial.

However, atmospheric lifetime and global-warming potential are not the only environmental criteria that matter.

A complete assessment should also examine:

• Atmospheric transformation products
• Environmental persistence
• Mobility through water and soil
• Toxicity and ecotoxicity
• Bioaccumulation potential
• Waste and end-of-life releases
• Occupational exposure
• Leakage during equipment servicing
• Cumulative emissions as adoption increases
• The availability of lower-impact alternatives

The new research focuses on one of these overlooked dimensions: what the replacement refrigerant becomes after it enters the atmosphere.

How refrigerants become TFA

Refrigerants can escape during vehicle operation, maintenance, accidents, equipment failure or end-of-life handling.

Once released, atmospheric oxidants react with the refrigerant molecules and produce other compounds.

Both HFC-134a and HFO-1234yf can ultimately contribute to the formation of TFA. However, HFO-1234yf is more chemically reactive and produces TFA more rapidly and at a higher yield than HFC-134a.

Because HFC-134a remains in the atmosphere longer, it can travel farther before degrading. HFO-1234yf breaks down in approximately days rather than years, so its resulting TFA may be produced and deposited closer to major emission regions.

TFA is highly soluble in water and is removed from the atmosphere primarily through wet deposition.

This means rainfall can transfer atmospherically generated TFA into:

• Rivers
• Lakes
• Reservoirs
• Groundwater recharge areas
• Soil
• Vegetation
• Agricultural systems
• Coastal waters
• Drinking-water sources

The environmental issue is therefore not confined to air pollution.

An atmospheric emission can ultimately become a water-quality and land-contamination concern.

What the Bristol study found

The researchers used a global tropospheric chemical transport model called STOCHEM-CRI.

The model incorporated refrigerant-emission estimates, atmospheric transport, chemical reactions and deposition processes. Atmospheric measurements from the Advanced Global Atmospheric Gases Experiment network were used to evaluate elements of model performance.

Using estimated 2023 emissions, the study found that:

• Estimated HFC-134a emissions were approximately 22 times higher than HFO-1234yf emissions.
• HFO-1234yf was nevertheless predicted to generate between 26% and 75% as much global TFA as HFC-134a.
• Maximum modelled surface concentrations were higher in the HFO-1234yf scenario.
• TFA production from HFO-1234yf was more concentrated near major emission regions.
• Modelled TFA deposition from HFO-1234yf was up to 3.6 times higher than that associated with HFC-134a across parts of Europe under the conservative comparison scenario.

The greatest modelled European enhancements occurred over Italy and parts of Austria, Germany, Switzerland and France.

The study therefore concluded that HFO-1234yf may already have a greater influence on TFA generation and deposition in Europe than HFC-134a.

This was modelling, not direct global measurement

The findings are important, but they require careful interpretation.

The study used atmospheric modelling informed by available emissions estimates and measurement data. It did not directly measure TFA deposition at every location included in the model.

The researchers identified major uncertainties concerning:

• Global HFO-1234yf emissions
• The geographical distribution of emissions
• The proportion of HFC-134a that forms TFA
• Conditions affecting atmospheric transport and deposition
• Estimates outside regions with stronger emissions information

The model’s predictions for North America, East Asia and other regions were considered more uncertain because global HFO-1234yf emissions had to be estimated from limited regional information and scaled assumptions.

This means the research should not be interpreted as proof that a particular concentration exists in Trinidad and Tobago or elsewhere in the Caribbean.

No Caribbean TFA monitoring data were presented in the paper.

Instead, the findings identify a plausible global source that deserves improved emissions tracking and environmental measurement as HFO-1234yf use expands.

Why persistence and mobility matter

Environmental risk is influenced not only by toxicity but also by how long a chemical remains and how easily it moves.

TFA is a small, highly mobile compound. Once released into the water cycle, it can be difficult to contain and remove.

Research indexed by the US Environmental Protection Agency has reported that commonly used treatments such as ozonation and granular activated carbon were ineffective for removing TFA in the studied systems. Biological wastewater treatment also did not remove it effectively, while reverse osmosis achieved much stronger retention.

This matters because prevention becomes especially important when a pollutant is:

• Persistent
• Highly water-soluble
• Mobile through environmental systems
• Difficult to remove through conventional treatment
• Produced continuously from multiple precursor chemicals

A pollutant does not need to accumulate strongly in organisms to create a long-term environmental burden.

Persistent and mobile substances can spread through water systems and become difficult to manage once concentrations increase.

Hazard classification and environmental risk are related but different

In June 2026, the European Chemicals Agency’s Risk Assessment Committee adopted an opinion supporting classification of TFA as toxic to reproduction, Category 1B, as well as persistent, mobile and toxic and very persistent and very mobile.

This regulatory development increases concern about continued environmental releases.

However, a hazard classification is not the same as proving that current environmental concentrations are causing a particular health effect in every exposed population.

Hazard asks whether a substance is capable of causing harm under relevant conditions.

Risk also considers:

• Environmental concentration
• Exposure level
• Route of exposure
• Frequency
• Duration
• Vulnerability of the exposed population
• Scientific uncertainty

The scientific paper notes that ecotoxicity information remains limited and that there has been little evidence of toxicity at concentrations currently observed in the environment, while also emphasising that environmental concentrations are increasing and knowledge gaps remain.

The appropriate response is therefore neither complacency nor exaggeration.

It is better measurement, improved source identification and precautionary management of increasing releases.

The problem of regrettable substitution

A regrettable substitution occurs when one chemical is replaced by another that solves the original problem but creates a different environmental or health concern.

This does not necessarily mean the replacement was irrational.

Environmental decisions are often made using the best evidence available at the time. New research can reveal impacts that were previously uncertain or poorly measured.

The important lesson is that replacement decisions should use a broad evaluation framework.

For refrigerants, that framework should consider:

1. Ozone-depletion potential.
2. Direct global-warming potential.
3. Energy efficiency during use.
4. Atmospheric degradation products.
5. Persistence and mobility.
6. Toxicological and ecotoxicological properties.
7. Flammability and operational safety.
8. Leakage rates.
9. Recoverability and recycling.
10. End-of-life management.

A refrigerant that performs well against one criterion may perform less well against another.

Environmental decision-making should therefore compare the complete performance profile rather than relying on a single sustainability label.

Why vehicle servicing matters

Refrigerant emissions do not occur only during normal driving.

They may also occur during:

• Air-conditioning repair
• Refrigerant recharging
• Vehicle collisions
• Hose or seal failure
• Poor maintenance
• Unauthorised venting
• Equipment dismantling
• Scrapping and recycling
• Improper disposal

Good refrigerant management can reduce unnecessary releases regardless of which chemical is being used.

Relevant controls include:

• Leak detection
• Proper refrigerant recovery
• Technician training
• Maintenance records
• Secure storage
• Certified recovery equipment
• Responsible recycling or destruction
• Inspection of end-of-life vehicles
• Prevention of deliberate venting
• Measurement of national refrigerant imports and use

The Bristol researchers highlighted the absence of a comprehensive global framework for monitoring HFO production and emissions. Better information on where and how much HFO-1234yf is released is needed to improve future estimates of TFA formation and deposition.

Why the research matters for the Caribbean

Vehicle air conditioning is an important practical requirement in tropical countries.

As newer vehicles enter Caribbean markets, HFO-1234yf use is likely to become increasingly relevant to regional refrigerant management. That creates questions concerning imports, servicing practices, technician capability, refrigerant recovery and end-of-life vehicle handling.

However, the Bristol study did not measure Caribbean emissions or TFA concentrations.

The appropriate regional conclusion is therefore not that Caribbean water is already contaminated at a particular level.

It is that emerging international evidence provides a reason to improve baseline knowledge before potential contamination becomes more difficult to manage.

Useful regional questions include:

• How much HFO-1234yf is imported annually?
• How many vehicles use the refrigerant?
• How much is lost during servicing?
• Are technicians equipped to recover it?
• How are damaged and end-of-life vehicles managed?
• Is TFA included in any surface-water, groundwater or rainwater monitoring?
• Are laboratories able to detect it at environmentally relevant concentrations?
• Which drinking-water sources may be vulnerable to persistent mobile contaminants?

These questions link chemical management, automotive servicing, air emissions and water-quality protection.

Environmental monitoring must match the pollutant pathway

A monitoring programme for TFA would need to reflect how it enters and moves through the environment.

Potential sampling media could include:

• Rainwater
• Surface water
• Groundwater
• Drinking-water sources
• Wastewater
• Soil
• Vegetation
• Coastal water

Monitoring locations might be selected near:

• Dense urban traffic
• Vehicle-service clusters
• Vehicle-storage and dismantling facilities
• Industrial refrigeration activity
• Waste-management sites
• Water-supply catchments
• Background locations for comparison

Repeated sampling would be more informative than a single isolated test.

Rainfall, seasonal conditions, atmospheric transport and changing refrigerant use could all influence measured concentrations.

Analytical method selection is critical

TFA is not a routine parameter in many standard water-quality programmes.

Testing requires a laboratory method suitable for a small, highly polar and mobile compound.

Before samples are collected, a project should confirm:

• The laboratory’s analytical method
• The reporting and detection limits
• Sample containers
• Preservation requirements
• Holding times
• Field blanks
• Laboratory blanks
• Recovery and quality-control procedures
• Potential interferences
• Whether results represent TFA or total fluorinated substances

TFA should not be treated as interchangeable with every other PFAS measurement.

A laboratory may offer analysis for a standard PFAS list without including TFA. The required analyte list must therefore be confirmed explicitly.

Poorly planned sampling can produce results that are scientifically weak or impossible to compare.

Baseline monitoring creates future value

Countries and industries often begin monitoring only after international concern becomes urgent.

By that stage, it may be difficult to determine:

• When contamination began
• Whether concentrations are increasing
• Which source is dominant
• Whether controls are effective
• Whether the pollutant was already present before a new activity started

Baseline monitoring provides a reference point.

Even where current concentrations are low, well-designed baseline data can help regulators and industries detect future changes early.

It can also support:

• Chemical policy
• Water-resource management
• Vehicle-refrigerant regulation
• Occupational guidance
• Waste-management planning
• Public communication
• Environmental impact assessment
• Source-reduction programmes

How Ecotox can support emerging-contaminant investigations

Ecotox Environmental Services can support environmental investigations through:

• Surface-water sampling
• Groundwater sampling
• Rainwater sampling programmes
• Wastewater sampling
• Soil and sediment sampling
• Environmental baseline studies
• Environmental analytical testing coordination
• Emerging-contaminant sampling plans
• Waste characterisation
• Quality-assurance and chain-of-custody procedures
• Environmental compliance monitoring
• Interpretation of environmental results

For specialised contaminants such as TFA, the analytical laboratory, method, detection limits and sample requirements should be confirmed before fieldwork begins.

Ecotox can help connect the field-sampling programme with an appropriate analytical and quality-assurance strategy.

Learn more about Ecotox Environmental Analytical Testing Services.

Climate solutions need lifecycle evidence

Replacing HFC-134a with HFO-1234yf addressed a legitimate climate concern.

The newer refrigerant has a lower direct global-warming impact, but new evidence suggests that its atmospheric degradation may create an increasing burden of persistent TFA contamination.

This does not mean that society should return automatically to the older refrigerant.

It means the environmental evaluation must continue.

Future refrigerant policy should consider climate effects, atmospheric chemistry, water contamination, toxicity, safety, emissions control and end-of-life management together.

The wider lesson applies far beyond vehicle air conditioning:

A technology is not environmentally preferable merely because it performs better against one indicator.

Responsible substitution requires lifecycle assessment, transparent evidence and monitoring of unintended consequences.

When new risks emerge, environmental science must be able to detect them early enough for industry and policy to respond.

Sources

University of Bristol — Replacement ‘climate-friendly’ car refrigerant linked to rising forever chemical pollution in Europe
https://www.bristol.ac.uk/news/2026/july/replacement-climate-friendly-car-.html

Environmental Science & Technology Letters — TFA Generation and Deposition over Europe May Currently See a Greater Influence from HFO-1234yf than HFC-134a
https://doi.org/10.1021/acs.estlett.6c00356

European Chemicals Agency — Trifluoroacetic acid harmonised classification registry
https://echa.europa.eu/registry-of-clh-intentions-until-outcome/-/dislist/details/0b0236e188e6e587