Sasol's Secunda plant 'cleared' as source of stench over Gauteng and Mpumalanga two weeks ago 28 February 2021 - 16:06 Image: Tony Carnie The department of environment, forestry and fisheries (DEFF) said it will continue to probe the source of the stench experienced in parts of Gauteng and Mpumalanga two weeks ago after clearing Sasol's Secunda plant as being the culprit. In a statement, the department said it will look at other sources that could have contributed to the odour and extend its probe to power plants and waste water works that also emit hydrogen sulphide. According to the department, the stench was most likely a combination of elevated levels of sulphur dioxide and hydrogen sulphide.