Finland’s Radiation and Nuclear Safety Authority (STUK) said it has found small amounts of radioactive isotopes of cobalt, ruthenium and caesium in air samples collected in Helsinki between 16 and 17 June. Radiation authorities in Sweden and Norway have reported similar findings.
Pia Vesterbacka, who heads environmental radiation surveillance at STUK, said there was no cause for alarm as the detected radioactive material was too minute to pose any risk.
"The amount of radioactive particles is very small and has no impact on the environment or human health," she explained.
Samples from Finland’s seven other radiation monitoring stations have yet to be analysed.
"Investigations are still ongoing...at this point we would not want to come out and say the radiation originated in Russia," she said.
Also on Radio Free Europe [rferl.org], pointing to a tweet [twitter.com] of Lassina Zerbo, the head of the Comprehensive Nuclear-Test-Ban Treaty Organization, tweet that shows a map of the possible source region in the 72h preceding detection.