R1234yf MAC refrigerant consist of highly toxic carbonyl fluoride

R1234yf MAC refrigerant consist of highly toxic carbonyl fluoride

Chemists at Ludwig Maximilians Universität München report that 20% of the gases produced by the combustion of R1234yf—the approved low global warming potential refrigerant for mobile air conditioning (MAC) systems, the adoption of which has met with resistance from German automakers —consist of the highly toxic chemical carbonyl fluoride.Carbonyl fluoride is structurally related to phosgene (which contains chlorine in place of fluorine), which was used as a chemical weapon during the First World War. Kornath and his co-workers have just published the results of their investigation in the journal Zeitschrift für Naturforschung B.


It has been known for some time now that combustion of R1234yf results in production of the toxic hydrogen fluoride. Our analysis has now shown that 20% of the gases produced by combustion of the compound consist of the even more poisonous chemical carbonyl fluoride.

The simplest fluoride, hydrogen fluoride (or hydrofluoric acid, HF) is also highly corrosive and so toxic that burns about as big as the palm of one’s hand can be lethal. The agent binds avidly to calcium in body fluids, and this can result in heart failure unless an antidote is rapidly administered.

Carbonyl fluoride is even more dangerous, because it penetrates the skin more easily, and causes severe irritation of the eyes, the skin and the airways. If inhaled, it can damage the alveoli in the lungs, allowing it to reach the circulation and shut down vital functions.

According to guidelines issued by the European Union, automobile manufacturers are legally obligated to use a low global warming potential refrigerant in the air-conditioning systems installed in their cars. Use of the previously approved refrigerant R134a in new models has been forbidden in the EU since 2011, as the agent had been shown to contribute to the global warming in the atmosphere.

However, R1234yf, the recommended replacement , has already been the subject of much heated debate in Germany. Studies carried out by various institutions and by German auto manufacturers had pointed to the compound’s flammability, and shown that, in the event of accidents in which vehicles catch fire, combustion of R1234yf leads to the release of hydrogen fluoride.

An interim report in 2013 based on independent testing by Germany’s Kraftfahrt-Bundesamt (Federal Motor Transport Authority) found that there is “no sufficient evidence of a serious risk” as defined by the Product Safety Act (ProdSG) related to the use of the low global warming potential (GWP) refrigerant R-1234yf.

KBA found that in the most severe crashes (level 3), one of the four models ignited and emitted toxic hydrogen fluoride (HF) gas; “non-negligible amounts” of HF were also found in two other test crashes. However, the level 3 crash testing was outside of the bounds of the statutory scope of product safety regulations—i.e., the level 3 tests could not be associated with the necessary concrete probability of occurrence, but served as a general appraisal of the risk.

More recently, a scientific review of research regarding the safety aspects of the use of refrigerant R1234yf in Mobile Air Conditioning (MAC) systems, published by the European Commission, also shared the conclusion that there is no evidence of a serious risk in the use of this refrigerant in MAC systems under normal and foreseeable conditions of use under product safety guidelines.

That review, carried out by Europe’s Joint Research Centre, provided an in-depth analysis of testing and a subsequent report on the refrigerant’s safety by KBA in order to ascertain whether the results stemming from the tests were well founded and supported by a rigorous and scientific methodology.

Based on the LMU results, however, Professor Kornath is urging a re-assessment.

The risk analyses carried out by the manufacturers of the refrigerant so far have not taken carbonyl fluoride into account. In light of our results, we advise that the risks associated with R1234yf should be urgently reassessed.