Forty years ago, on 26 April 1986, the nuclear reactor in Chernobyl, Ukraine, exploded. Large quantities of radioactive material were scattered across Europe. Austria was severely affected by radioactive fallout – caused by rainfall in the days following the release: the areas where it rained the most also received the highest levels of radioactive material, known as radionuclides. Particularly in Upper Austria, Salzburg, north-western Styria and parts of Carinthia, elevated levels of the long-lived caesium-137 can still be measured today.