Overview
- The environment department said reports from 10 March were likely caused by hydrogen sulphide, with SAAQIS data showing peaks at Secunda, Springs, Irene, Midstream and Buccleuch that exceeded the WHO nuisance-odour threshold of 5.02 ppb.
- Meteorological analysis indicated south-easterly winds probably carried polluted air from Mpumalanga into Ekurhuleni, Johannesburg and Pretoria during the episode.
- Johannesburg’s monitoring network logged hydrogen sulphide around 36–37 ppb in Alexandra and sulphur dioxide near 52 ppb between 9 and 11 March, prompting a city investigation coordinated with provincial and national authorities.
- Government is advancing reforms to cut hydrogen sulphide limits from coal gasification from 3,500 mg/m³ to 600 mg/m³ and to classify the gas as a criteria pollutant to enable national ambient standards, with a second consultation round and finalisation expected in 2026.
- Officials advised residents to report persistent odours, reduce exposure when the smell is present, and seek medical care for ongoing respiratory irritation or other symptoms.