Monitoring stations record upward trend, but expert says it could be explained by natural causes
The radiation level in Changbai Korean autonomous county – the closest Chinese urban area to the Punggye-ri test facility – climbed gradually from an average of 104.9 nanograys per hour immediately after the test on Sunday to 108.5 on Tuesday, according to figures released by China’s environment ministry.The changes could be down to environmental factors and unrelated to the nuclear test, but the trend was “worthy of attention”, said a scientist who sits on a panel that advises the Chinese government on emergency responses to radioactive hazards.
By Wednesday morning the average level in the county, which lies about 80km west of the blast site, had risen to 110.7 with a peak of 112.5.
Nanograys per hour is the standard unit for measuring the absorption of radiation by human tissue.
Similar upward trends were reported by monitoring stations in other regions, including in Antu county at the foot of Changbai Mountain and in Yanbian Korean autonomous prefecture further north.
Guo Qiuju, a professor of radiation protection at the school of physics at Peking University, said it was too early to be certain what had caused the rising trend at the monitoring stations as radiation levels change over time even under normal conditions.
The public had no need to panic as no suspicious trace elements were detected by the government on Tuesday, she said.
“If something bad had happened I would be one of the first to be informed,” she said. “I have not received the call so far.”
The current radiation levels were far below anything that could be regarded as a risk to people’s health, she said, “but if the figures keep going up it may require a closer look”.
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