Tiny amount of radioactive iodine measured in Tromsø

The measurement was seen when the filter at the directorate’s High North laboratory in Tromsø for the week March 21-26 was analyzed.
Norway’s Nuclear Safety Authority says in a short  statement  that the origin of the isotope measured in air in Tromsø for now is unknown.
None of the other radiation filter stations in Norway or in other Nordic countries have reported detection of Iodine-131 in recent weeks.
There are such radiation filters at Svanhovd in the Pasvik valley near the border with Russia, as well as in Rovaniemi, northern Finland.
Tiny amounts of radioactive Iodine have previously been measured at different locations in Northern Europe, but for the most it has been difficult to point to from where the releases are coming.