Air conditioning systems for passenger cars in the EU must switch to a new refrigerant for the sake of climate protection. However, UBA is not the only one to believe that many car manufacturers are backing the wrong horse. The new refrigerant R1234yf can ignite during accidents and hydrofluoric acid may form. This is what tests commissioned by UBA and the German Federal Motor Transport Authority (KBA), and others, have shown. Car occupants and rescue workers in particular may be potentially at risk. After having reviewed the KBA’s tests, the European Commission’s Joint Research Centre nevertheless sees no serious risk and fully disregards results from other studies. UBA finds this incomprehensible.