The department said late on Wednesday: “The stench is likely a combination of elevated levels of sulphur dioxide and hydrogen sulphide.” Sulphur dioxide is a potentially toxic gas often associated with volcanic eruptions, and there are no active volcanoes in the area. Hydrogen sulphide is highly toxic. The former emits the smell of burnt matches, the latter’s is akin to rotten eggs. Mix the two and you get a putrid stench. 

“People who are sensitive to unpleasant odours are likely to experience headaches and nausea,” it said. “While there are many sources in the area that could be contributing to these elevated levels, the district municipality’s air quality officer has been informed that the Sasol Secunda operation is experiencing stressed conditions as the facility started ramping up operations.” 

Air quality monitoring had revealed that while the levels were elevated, they “remained in compliance with ambient standards in Johannesburg, Pretoria and Mpumalanga”.

Sasol, in a statement dated Tuesday, 16 February, said: “Sasol can confirm that recently our Secunda operations in Mpumalanga have been stable with no operational incidents that have/could have resulted in an increase in sulphur emissions.”

It also noted that “sulphur ambient air quality standard limits as set by the government” had not been exceeded. 

If the department and Sasol both say the levels have not been breached, it raises the question: why was the probe launched in the first place? But something foul is in the air so the department can hardly be faulted for being proactive.

Sasol is very sensitive to its environmental record, which is under growing scrutiny since it is the second-biggest emitter, after Eskom, of the greenhouse gases linked to climate change in South Africa. On Monday, when it releases its interim financial results, its executives will no doubt face questions about the department probe.

And pollution is very topical at the moment in the wake of Wednesday’s release of a scathing report by the South African Human Rights Commission on the raw sewage befouling the Vaal River courtesy of a dramatic failure of governance by the Emfuleni Local Municipality. Whether it is in the water or the air, South Africa is dealing with serious pollution issues which have social, health and economic consequences. BM/OBP