The 'Climate-Friendly' Refrigerant In Your Car's AC May Not Be So Friendly After All

There's no denying that air conditioning was among the most important inventions of the 20th century. On top of allowing us to live in hotter climates, it also helps us transport produce and sensitive medicines without letting them spoil. While we've almost perfected the A/C formula, the refrigerant is a whole different story. We've changed automotive refrigerants several times over the years, but it seems the latest one, HFO-1234yf, is still causing environmental problems.

You might remember learning about chlorofluorocarbons (CFCs) in school — as well as the giant hole they made in our ozone layer. One of the CFCs responsible for this damage was R-12, which we once used in automotive air conditioning systems. We replaced R-12 in the 1990s (barring some suggestions of illegal production) with R-134a, which helped to recover the ozone layer. But it turned out to have a high global warming potential, producing the equivalent of 1,430 kg of carbon dioxide for every kilogram of R-134a in the atmosphere.

This led to the adoption of yet another new refrigerant, HFO-1234yf, to address the problems of R-134a. However, it seems we still haven't figured out A/C refrigerants. According to a new study led by the University of Bristol, HFO-1234yf is causing a spike in trifluoroacetic acid (TFA), a major "forever chemical" that can enter the bloodstream and affect a person's liver. Some studies have also linked TFA exposure to reproductive problems.

The "HFO" prefix of HFO-1234yf means that it is a hydrofluoroolefin. Unlike HFC-134a, it contains a carbon-carbon double bond, which makes it much more reactive in the atmosphere. According to the study, when HFO-1234yf breaks down in our atmosphere, it forms TFA. It's virtually non-biodegradable, which means it does not go away and accumulates over time.

Yes, R-134a also produced TFA, but it did so in much smaller quantities. According to the study, HFO-1234yf could have already made 75% as much TFA as R-134a. This is a huge number, considering that R-134a was used from the 1990s to around 2017, and it hasn't even been a full decade since we started using its successor. HFO-1234yf emissions so far have been 22 times lower than R-134a, and it's still having a dramatic effect. Because European countries like Italy, Germany, Switzerland, and France were the first to adopt HFO-1234yf, most TFA is concentrated there. Given its harmful potential, discussions within the European Chemicals Agency's Risk Assessment Committee to label TFA as a Reproductive Toxicity Category 1B, a "persistent, mobile, and toxic (PMT) substance," and "very persistent and very mobile (vPvM)" are already underway.

As the world continues to transition away from R-134a to HFO-1234yf, greenhouse gas emissions will drop. At the same time, though, more TFA is being generated. We also don't yet have comprehensive monitoring systems for HFOs. Even increasing electric car adoption won't help, as EVs also use refrigerants to keep their cabins cool. Governments and manufacturers, like Honeywell and DuPont, will need to find a solution together.