Small amounts of radioactive isotopes have been detected in air samples collected in Kotka in south-east Finland, but there is no risk to humans and similar discoveries are "quite normal", the country's nuclear safety watchdog said on Wednesday.
"The observed radioactivity has no impact on the environment or human health, as the concentrations were very low," the Radiation and Nuclear Safety Authority (STUK) said in a statement.
Finland, Sweden, Russia and the wider region have a number of nuclear power reactors.
"Small amounts of zirconium and niobium can escape into the air, for example, from the fuel of a nuclear power plant during plant maintenance," STUK said.
During the collection of the sample, air currents were flowing to Kotka from the east and southeast, but the source of the radiation was unknown, it added.
STUK did not plan to investigate further as such discoveries are "quite normal", a spokesperson for the agency said.
(Reporting by Terje Solsvik, editing by Stine Jacobsen)