Minuscule traces of radioactive silver were found in South Korean atmosphere for the first time Saturday since Japan’s nuclear accident, the Korea Institute of Nuclear Safety said.

The substance was detected in air samples taken from the central city of Daejeon and the southeastern city of Daegu, the agency said. Radioactive iodine and cesium had been found in South Korean air before, but it was the first detection of radioactive silver since the Japanese nuclear crisis.

The agency said, however, that the detected amounts were so small that they pose little health risk to humans. The daily dose was about one-3,700th of the radiation emitted in a chest X-ray, it said.

Traces of radioactive iodine were also found in 11 of the 12 checkpoints across the nation, but the amounts gave a daily dose of about one-1,800th of a chest X-ray, the agency said.

Radioactive cesium was not found at all checkpoints, it said.

South Korea has been keeping a close watch over radiation levels since the March 11 quake hit the nuclear power plant in the coastal Japanese city of Fukushima.

Radiation levels on South Korea’s easternmost islets of Dokdo were far lower than those on the nearby island of Ulleung that is located further away from Japan grappling with a quake-hit atomic power plant, the nuclear safety institute said Saturday.

Korea set up radiation detection equipment on Dokdo on Friday amid rising fears of radioactive substances drifting from Japan’s quake-hit Fukushima nuclear power plant. The move was also apparently aimed at demonstrating that Dokdo is South Korean territory as Japan renewed its claims over the islets.

The newly established equipment checks radiation levels on Dokdo every five minutes and sends the data to the state-run KINS based in Daejeon.

According to the agency, radioactive levels on Dokdo were measured at 99 nanosieverts per hour as of 11:20 a.m., lower than 138 nanosieverts gauged at the same time on Ulleung, about 93km northwest of Dokdo.

Normal radioactive levels in South Korea range from 50-300 nanosieverts per hour.

The agency said that the lower levels on Dokdo were believed to be because the device there was set up on a rock above ground while the equipment on Ulleung was installed on ground that emits spontaneous radiation.

(From news reports)