Helen ApSimon founding member and Chairman of the European Association for the Science of Air Pollution. ApSimon is well known for her research into the transport of radioactivity from the Chernobyl disaster. In the immediate aftermath, Russia issued a media blackout and ApSimon was one of few European scientists to detect rising radiation levels. She modelled the nuclear fallout, calculating Chernobyl released 15 - 20 megacuries of Iodine-131 and 1 - 2 megacuries of caesium-137. During the first few weeks after the disaster, ApSimon calculated the radioactive plum covered Scandinavia and the North coast of Europe. She travelled to Hungary, Poland, Czechoslovakia
Radiation effects from the Fukushima Daiichi nuclear disaster Iwate), in Saku, Karuizawa and Sakuho (prefecture Nagano, in Tabayama (prefecture Yamanashi) and elsewhere. Based on radiation measurements made all over Japan between 20 March and 20 April 2011, and the atmospheric patterns in that period, computer simulations were performed by an international team of researchers, in cooperation with the University of Nagoya, in order to estimate the spread of radioactive materials like caesium-137. Their results, published in two studies on 14 November 2011, suggested that caesium-137 reached up to the northernmost island of Hokkaido, and the regions of Chugoku and Shikoku in western Japan at more than 500 kilometers