HELSINKI, March 8 (Xinhua) -- The Radiation and Nuclear Safety Authority of Finland (STUK) has detected an exceptionally high amount of radioactive cesium in the air here, local media revealed on Tuesday.
The radioactive cesium-137 was found on Thursday and Friday last week in samples collected by a STUK's monitoring station located in Roihupelto, eastern Helsinki.
The level of cesium in the air is unusually high, although the amount was not high enough to affect human health, according to STUK.
The measured result, 4,000 microbecquerels per cubic meter of air, is about a thousand times higher than the normal status.
Risto Isaksson, spokesman of STUK, told the Finnish daily Iltalehti that the detected amount of cesium corresponds to findings in Finland in the spring and summer following the fallout of the Chernobyl nuclear power plant accident which occurred in April 1986.
He added that the substance can spread over a long distance by wind.
Since the Chernobyl accident, the radioactive substance has been detected regularly in Finland.
Tarja K. Ikaheimonen, research director of STUK, told daily Helsingin Sanomat that such a concentration had not been observed for a long time. The recent detected amount of cesium was 10 times higher than what spread from the Fukushima accident in Japan to Finland five years ago.
STUK has also ruled out the possibility that the cesium would have come from a nuclear reactor, because the sample contains only cesium-137.
What has been known at the moment is that the wind blew from the east and southeast, when the substances were discovered, said STUK.
The authority will continue to investigate the source of the radioactive cesium.