By Will Atwater

Driving in a North Carolina summer can be miserable without reliable air conditioning. 

Nonetheless, checking for a refrigerant leak isn’t part of a routine check under the hood, said “Crazy” Charlie Thompson, owner of C and C Automotive in northeast Durham. By the time a driver notices a problem, some refrigerant may already have escaped.

“When angel breath quits blowing on them, that’s when they are like, ‘Huh, we need some more Freon,’” Thompson said.

Drivers often buy small cans of refrigerant to recharge their systems themselves. Some products contain only refrigerant; others include sealants intended to stop leaks. Thompson said those sealants can clog his shop’s refrigerant-recovery equipment.

“When they introduce that to their system, it stops up our $25,000 reclaimer, and they don’t want to pay us for that,” he said.

Familiar refrigerants, such as Freon, have evolved to address environmental concerns. But some of the newer alternatives come with a trade-off: Chemicals used to reduce coolant’s climate impact end up breaking down in the atmosphere into trifluoroacetic acid, or TFA, a pollutant that persists in the environment.

Many researchers classify TFA as an ultrashort-chain per- and polyfluoroalkyl substance  presenting yet another challenge for North Carolina communities already grappling with how to remove PFAS from drinking water — and how to pay for that removal.

Cape Fear Public Utility Authority draws much of its drinking water from the Cape Fear River, which has been contaminated by decades of PFAS releases from an upstream chemical plant operated by Chemours and its predecessor, DuPont. 

As of April 2026, the utility had spent $91 million addressing PFAS contamination in its drinking water supply, WilmingtonBiz reported. But all that money hasn’t been able to stop TFA, according to the agency. Even as their granular activated carbon filters have reduced most of the PFAS it monitors to levels at or near nondetection, some ultrashort-chain compounds, like TFA, are harder to capture. 

Researchers have detected TFA in tap water served by CFPUA’s Sweeney Water Treatment Plant. Those detections do not establish where the TFA came from, but they illustrate the challenge: Treatment is an imperfect solution to the PFAS problem.

“There isn’t really a silver bullet,” said Richie Kaur, senior superpollutant reduction advocate for climate and energy for the Natural Resources Defense Council. “There’s not a perfect refrigerant in the world. If we had it, we would have used it.”

A history of trade-offs

Refrigerants perform a basic job in refrigerators and air conditioners: moving heat.

“When you’re cooling something, the refrigerant is transferring heat from, say, inside the house and throwing it outside, and your house is cooled,” Kaur said.

Finding chemicals to do the job safely, efficiently and without harming the environment has driven successive changes in refrigerants.

Early refrigerants, used beginning in the 1800s, included ammonia, sulfur dioxide and carbon dioxide. Some posed toxicity or flammability hazards. By the 1930s, synthetic alternatives had begun to enter commercial use.

Those alternatives brought environmental problems. By the 1980s, scientists had linked ozone layer depletion to chemicals common in refrigerators, air conditioners and aerosol cans. The Montreal Protocol, adopted in 1987 and strengthened through subsequent amendments, set in motion their phaseout.

Hydrofluorocarbons became widely used replacements. They spared the ozone layer but were potent greenhouse gases. In 2016, countries adopted the Kigali Amendment, another internationally negotiated settlement, to phase down their production and consumption, with the first reductions beginning in 2019.

The search for alternatives helped usher in a newer generation of refrigerants that break down faster in the atmosphere and have a much smaller direct warming effect.

One of them, HFO-1234yf, is a compound made of hydrogen, carbon and fluorine, now used in most light-duty vehicles, according to the U.S. Environmental Protection Agency. The EPA says its global warming potential is hundreds of times less than predecessor compounds, and it breaks down easily.

But when  HFO-1234yf escapes into the air, it breaks down into TFA.

Chronic exposure

Scientists are still working out what widespread TFA escape means for people and the environment. A 2024 review documented its presence in rain, soil, drinking water and other parts of the environment, warning that its extreme persistence and continued releases are driving its accumulation.

Ultrashort-chain PFAS such as TFA pass through the body more quickly than some longer-chain PFAS, which can persist for a long time in human tissue. Nonetheless, humans are chronically exposed to these quickly moving chemicals because they’re highly present and persistent in the environment, said Anna Reade, director of PFAS advocacy and environmental health for the Natural Resources Defense Council.

Reade also noted that “health research has lagged behind the emergence of these chemicals. 

“We’re kind of at a very early stage of understanding the impacts that TFA can have on human health,” she said. “But already in that early stage, we are seeing some health effects that are also shared with other PFAS, like reproductive harm and thyroid disruption.”

U.S. research on these chemicals is lagging behind work being done in Europe, where regulators use a different definition of harm, said Lee Ferguson, a Duke University professor of civil and environmental engineering. He said that may be why there’s been more focus on the effects of TFA across the Atlantic.

The EPA is starting to take steps to learn more about TFA in drinking water. In a proposed rule published in July, the agency included TFA among 30 unregulated chemicals that public water systems would monitor between 2028 and 2030. The findings would help inform future decisions about whether to regulate the contaminants. 

The proposal would not set a drinking water limit for TFA.

What’s next for refrigerants?

Nearly 300 million light-duty vehicles were registered in the United States in 2025, including about 9 million in North Carolina, according to U.S. Department of Energy data. Those numbers illustrate the enormous scale of automotive cooling and its potential to contribute to TFA pollution — even though not every vehicle uses a refrigerant that breaks down into TFA.

Many vehicles will lose refrigerant at some point, but the EPA does not require leak repairs before a vehicle’s air conditioning system is recharged, although state or local requirements may differ.

A fully charged vehicle air conditioning system can hold about two pounds of refrigerant, estimated Jeremy Arling, a senior fellow specializing in super pollutants at the Natural Resources Defense Council. Those systems are exposed to heat and vibration, and the refrigerants end up escaping through tiny gaps in the rubber seals. 

“Over the life of a car, you probably will lose your whole charge,” he said.

Reducing leaks is one challenge. Choosing what goes into cooling systems is another.

The Kigali Amendment was intended to push countries to reduce production and consumption of older refrigerants that affected the environment, but it does not dictate which refrigerants replace them.

Across refrigeration and air conditioning, alternatives include carbon dioxide, ammonia and propane, said Kaur, a senior scientist for the National Resources Defense Council. Carbon dioxide can be less efficient in hot climates, propane is highly flammable, and ammonia is toxic and mildly flammable.

The EPA already allows carbon dioxide in air conditioning systems in new vehicles, subject to safety requirements, but it does not permit propane for that use.

“But now the question is, what do we want to go to?” Kaur said.

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