A task team has been appointed to investigate the source of the smell of sulphur over parts of Gauteng and the North West this week.
It comprises environmental and air quality officials from the department of forestry, fisheries and the environment and its provincial counterparts in Mpumalanga, Gauteng, North West and the Free State. The team will submit a detailed report on the air pollution incident by next week.
The department said a meeting on Thursday “formally initiated” an investigation into the origins of the sulphurous odour, “which is thought to be, in all likelihood, due to a combination of above average ambient levels of sulphur dioxide (SO2) and/or hydrogen sulphide (H2S) in the air given the nature of this odour”.
The team will also devise a proactive long-term programme to improve the management of SO2 and H2S emission sources “beyond the responses triggered by public complaints”.
In February last year, similar sulphurous odour episodes were experienced over Mpumalanga and Gauteng. Investigations had focused on Sasol’s Secunda operations, “because these facilities are known to be the significant contributors of SO2 and H2S emissions”, the department said. These investigations were inconclusive and no further action could be taken.
“The task 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 SO2 or H2S into the atmosphere.”
Ambient air quality monitoring reports on the state of air in the region over the past month will be studied, focusing on the two toxic gases.
Ambient air quality monitoring observations on the South African Air Quality Information System show that SO2 ambient levels, while elevated, are compliant with ambient standards in Gauteng, the department said.
“However, preliminary results show significantly elevated levels of H2S around the Irene monitoring station in Centurion on 7 June. Possible sources that could influence such levels will be identified from the meteorological assessment.”
The team will investigate 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.”
For the long-term plan, officials will undertake a detailed assessment of H2S 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.”
The department said that for atmospheric emission licence holders, emission reductions and management plans will be established to improve the monitoring and management of H2S “to reduce the risks of ongoing pollution episodes that are affecting the provinces”.
Hydrogen sulphide (H2S)
Hydrogen sulphide is a colourless, flammable, hazardous gas with a strong odour of rotten eggs. It is produced by the breakdown of animal wastes or manure. It is heavier than air and can collect in low-lying and enclosed, poorly ventilated areas such as reception pits, ditches, or manholes.
Exposure to hydrogen sulphide may cause irritation to the eyes and respiratory system. It can also cause apnoea, coma, convulsions, dizziness, headache, weakness, irritability, insomnia; stomach upset and, if liquid, frostbite.
Workers at risk of being exposed to H2S include factory workers in plants where rayon textiles are manufactured, petroleum and natural gas workers involved in drilling and refining, workers in wastewater treatment industries and agricultural workers on farms with manure storage pits or landfills
Sulphur dioxide (SO2)
Sulphur dioxide is a colourless gas with a pungent odour. Exposure to SO2 may cause irritation to the eyes, nose, and throat. Symptoms include nasal mucus, choking, cough, and reflex bronchoconstriction and, when liquid, frostbite.
Inhalation is the major route of exposure. Most exposures are caused by air pollution and this has short-term and chronic health consequences for people with lung disease.
Sulphur dioxide is used in many industries such as manufacturing sulfuric acid, paper and food preservatives. Examples of workers at risk of being exposed to SO2 include factory workers where it occurs as a by-product such as copper smelting or power plants, industry workers who make sulfuric acid, workers in plants that produce paper and workers who manufacture fertilisers.