Some of the highest levels of poisonous gases in the air are found above Witbank, in Mpumalanga, and the surrounds, it was reported.
The levels of chromium and barium were so high that a European Union research team's instruments had been unable to take accurate measurements, Beeld reported.
The team had spent two years gathering data from the coal-rich catchment area of the Olifants River to determine whether environmental and social offences were taking place.
A South African member of the team, Dr Henk Coetzee of the Council for Geoscience, told the newspaper the EU was very aware of environmental legislation, human rights and sustainable development.
It had increasingly been hearing concerned voices from South Africa about coal mines encroaching on neighbourhoods and protected areas.
French geologist Stephane Chevrel, who led the project, reportedly said the EU and Israel had allocated about R48 million for the research.
According to Beeld, Gorazd Zibret, a geologist from Slovenia, said the levels of heavy metals in the air above the team's research area were, according to their information, the highest in the world.
He also said the raised levels had a negative affect on rivers and associated eco systems.
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