Are Our Refrigerants Safe? Scientists Raise Concerns Over New Cooling Chemicals

One of the newest refrigerants thought to be environmentally sound replacements, according to a new UNSW study, breaks down into lasting greenhouse gases. The study in the Journal of the American Chemical Society presents evidence that Hydrofluoroolefins (HFOs), widely used in refrigeration, air conditioning, and aerosol propellants, break down to minute levels of fluoroform, a highly reactive greenhouse gas that had earlier been prohibited due to its environmental effect.

Refrigerants are chemicals that phase from liquid to gas in an effort to transfer heat, and it is for this purpose that they are needed by cooling systems. The chemicals have changed over time because of environmental issues. The chemicals started off with chlorofluorocarbons (CFCs) being the trend but were discontinued once they were discovered to deplete the ozone layer. They were substituted with hydrofluorocarbons (HFCs), which, although ozone-friendly, have subsequently been discovered to possess high global warming potential. The phase-out of HFCs started globally in 2016 and resulted in the use of HFOs, which are regarded as more sustainable because of their shorter atmospheric lifetime.

Even though HFOs were thought to be less harmful, the UNSW research suggests otherwise. Researchers replicated atmospheric conditions in a lab experiment to determine what happens to HFOs when they decompose. What they found ensures HFOs disintegrate into chemicals such as trifluoroacetaldehyde, which also decomposes into fluoroform. Fluoroform is a high-global warming potential HFC that lingers in the air for up to 200 years and contributes heavily to global warming.

In order to examine these reactions, the researchers synthesized a gas mixture to simulate the atmosphere at different pressures and exposed them to lasers in order to replicate sunlight-driven reactions. They utilized several spectroscopic methods, including new ones tailor-made for the research, in order to track the breakdown process. The outcomes led to conclusions that although limited amounts of fluoroform are produced, its long atmospheric lifespan and enormous warming potential make it an issue.

Past disasters that were the result of the environment, like the ozone hole and lead petrol air pollution, were found when the massive damage was already there. The UNSW researchers are trying not to let that occur and figure out possible environmental damage prior to widespread harm. Their results are the first definite evidence regarding HFO breakdown and will be added to climate models in order to test for their long-term effects.

This is fresh information that will now be integrated into climate models by UNSW researchers and scientists globally to aid in further predicting the impacts of ongoing HFO use. Though there is still more work to be done, the research assists in bringing into focus the need for test-driving new chemical products prior to extensive use. Further research is to be conducted by the team to determine how various wavelengths of light influence the breakdown process, possibly releasing a greater or lesser amount of toxic byproducts.

Since HFOs are still being used on a broad scale, the research questions whether they are safe in the long term and whether policymakers need to reconsider their authorization. The results indicate that HFOs may be an improvement in refrigerant technology but are still potentially environmentally harmful.

Source: UNSW, Journal of the American Chemical Society (2025)