Radioactive material in emissions from coal burning does not significantly affect smog, authorities said on Thursday.

In response to a recent online discussion-that went viral - regarding smog hazards in northern China, environmental authorities clarified that the amount of radioactive material released into the air by coal-burning power plants is minimal and that the widespread conjecture that it was hazardous "lacks scientific basis".

For each gigawatt of electricity coal-fired power plants produce, only about 2.6 per thousand of the radioactivity in the coal is released into the air, an amount unlikely to pose a health hazard, the Ministry of Environmental Protection said in a statement released on Thursday.