A radionuclide of anthropogenic origin, Iodine-131, has recently been detected in tiny amounts in the ground-level atmosphere across Europe, IRSN, French public expert in nuclear and radiological risks, reports. Iodine-131 is a radionuclide with a short half-life (8 days), suggesting a rather recent release. So far, the source of the radiation remains a mystery.
According to the IRSN, the preliminary report states Iodine-131 was first found during week 2 of January 2017 in northern Norway but it was also detected in Finland, Poland, Czech Republic, Germany, France and Spain, until the end of January.
"Besides the iodine release, the origin of which is still unknown, the poor dispersion conditions due to the thermal stratification of the atmosphere also affected the observed concentration levels, including those of naturally occurring radionuclides such as Lead-210 (210Pb), or fine particles (PM2.5 and PM10) leading to pollution episodes, particularly in the Western part of Europe during week 4 of January," the institute said.
"It must be pointed out that only particulate iodine was reported. When detectable, gaseous iodine is usually dominant and can be estimated to be 3 to 5 times higher than the fraction of particulate iodine.
"In France, particulate Iodine-131 reached 0.31 µBq/m3 and thus the total (gaseous + particulate fractions) can be estimated at about 1.5 µBq/m3.
These levels raise no health concerns, IRSN said and added that the data has been shared between members of an informal European network called Ring of Five gathering organizations involved in the radiological surveillance of the atmosphere.
Finland and France went public with information, but the isotope was first detected in Svanhovd, Norway.
While Norwegian authorities argue the measurements had no news value, the event was important enough for both Europe and the United States to deploy the U.S. Air Force WC-135 Constant Phoenix to RAF base in Mildenhall, England, UK.
WC-135 Constant Phoenix, also called the nuclear explosion sniffer, is a special purpose aircraft used to collect samples from the atmosphere for the purpose of detecting and identifying nuclear explosions and tracking radioactive activity.
Featured image: WC-135 Constant Phoenix. Credit: U.S. Air Force