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 continue to monitor for long-term mental effects as they may not be present right away. On 24 May 2012, more than a year after the disaster, TEPCO released their estimate of radioactivity releases due to the Fukushima Daiichi Nuclear Disaster. An estimated 538.1 petabecquerels (PBq) of iodine-131, caesium-134 and caesium-137 was released. 520 PBq was released into the atmosphere between 12 and 31 March 2011 and 18.1 PBq into the ocean from 26 March to 30 September 2011. A total of 511 PBq of iodine-131 was released into both the atmosphere and the ocean, 13.5 PBq of caesium-134 and 13.6