According to the survey by the radioactivity monitoring stations across the country from April 11 to 17, iodine-131 and cesium-137 were found in the air above Wonsan and Chongjin. Their level in Wonsan was tested to be about 0.103mBq and 0.07mBq per cubic meter respectively and that in Chongjin 0.037mBq and 0.08mBq.

Trace amounts of iodine-131 and cesium-137 were detected in the rain that covered almost areas of the country on April 14.

The monitoring stations, set up in coastal areas including Chongjin, Hamhung, Wonsan and Haeju, are intensifying the survey into seawater, fish and sea plants since Japan discharged a large amount of contaminated water to the sea.