The Department of Forestry, Fisheries and the Environment (DFFE) has established a task team to investigate the complaints about the stench experienced over parts of Gauteng and North West in the past week.

"Following complaints about the strong sulphuric smell over Gauteng and parts of North West, officials have undertaken to immediately probe the possible source and cause of the stench and to submit a detailed report on the matter by next week," the department said in a June 10 media release.

Ambient air quality monitoring reports on the state of air in the region over the past month will be studied, focusing on sulphur dioxide and hydrogen sulphide.

Ambient air quality monitoring observations on the South African Air Quality Information System show that sulphur dioxide ambient levels, while elevated, are compliant with ambient standards in Gauteng, the DFFE noted.

However, preliminary results show significantly elevated levels of hydrogen sulphide around the Irene monitoring station in Centurion on June 7. Possible sources that could influence such levels will be identified from the meteorological assessment.

The team, comprising environmental and air quality officials from the DFFE and the provincial departments in Mpumalanga, Gauteng, North West and the Free State, will also devise a proactive long-term programme to improve the management of sulphur dioxide and hydrogen sulphide emission sources beyond the responses triggered by public complaints, the DFFE said.

Further, the team will investigate possible upset conditions experienced or reported by atmospheric emission licence holders over the past month that have had the potential to release large quantities of sulphur dioxide or hydrogen sulphide into the atmosphere.

"The task team will also probe possible sources through inspections and compliance assessment of emission monitoring reports against atmospheric emission licence requirements. Where non-compliances are identified, enforcement action will be taken," the DFFE assured the public.

For the long-term plan, the officials will undertake a detailed assessment of hydrogen sulphide sources in the four provinces. Atmospheric emission licence holders, wastewater treatment facilities and landfill sites will be prioritised as they are the most significant contributors.

"For the atmospheric emission licence holders, emission reductions and management plans will be established to improve the monitoring and management of hydrogen sulphide to reduce the risks of ongoing pollution episodes that are affecting the provinces.

"The long-term plans will strengthen the implementation of the Air Quality Management Plans in priority areas to ensure the reduction of air pollution once the Priority Area Regulations come into effect," the DFFE said.

Meanwhile, during February 2021, similar sulphurous odour episodes were experienced over Mpumalanga and Gauteng. Investigations by the department and atmospheric emission licensing authorities in the two provinces had focused on energy and chemicals multinational Sasol’s Secunda operations, because these facilities are known to be the significant contributors of sulphur dioxide and hydrogen sulphide emissions.

These investigations were, however, inconclusive and no further action could be taken.

"The task team will investigate the origins of the sulphurous odour, which are thought to be, in all likelihood, owing to a combination of above-average ambient levels of sulphur dioxide and/or hydrogen sulphide in the air, given its odour," the department said.