Residents across Johannesburg have been complaining about a strong sulphur-like smell hanging in the air for several days, prompting the City of Johannesburg to launch an investigation into the source of the odour.
The smell — widely described as similar to rotten eggs — has been reported in several areas across the city, including Sandton, Randburg, Roodepoort and Fourways. Some complaints have also come from areas beyond the city’s boundaries.
According to city officials, the unpleasant odour has been linked to the presence of hydrogen sulphide (H₂S), a gas commonly associated with the distinctive rotten egg smell.
The City of Johannesburg said its environmental monitoring teams began investigating the issue after residents first reported the smell earlier this week.
City Manager Floyd Brink said protecting residents’ health remains a priority while technical teams analyse air quality data.
“Our technical teams are actively monitoring air quality and working with other spheres of government to determine the source of the odour,” Brink said.
Data from air quality monitoring stations in Buccleuch and Alexandra showed elevated levels of hydrogen sulphide during the episode.
Tebogo Modiba, executive director of the city’s Environment and Infrastructure Services Department, said hydrogen sulphide levels recorded at the Alexandra monitoring station peaked at about 36 to 37 parts per billion. Levels of sulphur dioxide were recorded at roughly 52 parts per billion.
According to Modiba, while these levels were high enough to produce a noticeable smell, they remain below concentrations typically linked to serious health risks.
“Technical monitoring confirmed measurable odour-related compounds during the episode,” Modiba said.
Authorities say Johannesburg occasionally experiences transboundary pollution, and the matter has now been escalated to national and provincial environmental authorities to help identify the source.
Officials believe the smell may be linked to industrial emissions from the Highveld industrial complex, an area known for heavy industrial activity.
The city’s Air Quality Management Unit is continuing to analyse pollution data and atmospheric patterns to track where the odour originated and how it spread across the region.
In the meantime, residents have been advised to remain indoors when the smell is particularly strong and to avoid strenuous outdoor activities.
Health officials also warned that vulnerable groups — including children, the elderly and people with respiratory conditions — should watch for symptoms such as headaches, dizziness, eye irritation, throat irritation or fatigue.
The City of Johannesburg noted that the metro itself does not host major heavy industrial operations and that facilities operating within city limits are licensed and monitored by environmental inspectors.
Investigations into the source of the smell are ongoing.