All provincial areas on the Chinese mainland, apart from the Tibet Autonomous Region, detected "extremely low levels" of radioactive iodine-131 in the air, China's National Nuclear Emergency Coordination Committee said on Friday.

But the material poses no threat to public health or to the environment, said?a daily statement issued by the committee.

Guizhou Province found both iodine-131 and caesium-137, while Shandong, Guangdong and Hainan found iodine-131, caesium-137 and caesium-134.

Jiangxi, Hubei, Hainan, Yunnan and Xinjiang Uygur Autonomous Region reported radioactive substances for the first time yesterday, the committee said.

Low levels of radioactive isotope iodine-131 have also been detected in the air above the East China Sea, but the amount of radiation given off by the material is below one hundred-thousandth of the average annual exposure level to natural radioactive sources such as rocks, soil, food and the sun, said the statement. And no protective measures need to be taken against contamination from the material.

The committee's conclusion was based on monitoring and analysis results from the Beijing-based Regional Specialized Meteorological Center affiliated with the World Meteorological Organization and the International Atomic Energy Agency, the State Oceanic Administration and the Ministry of Environmental Protection, according to the statement.