One example of how air currents moving radioactive particles is the Chernobyl disaster. As the reactor started failing a large amount of radionuclides were released into the air which were then spread by air currents, leading to radiation that could be detected all the way in Sweden and other countries hundreds of miles away within a few days. The same occurred at the Fukushima Daiichi disaster. The spread of radioactive xenon gas, iodine-131, and caesium-137 could be detected on different continents many miles away