Scientists at the University of the Witwatersrand have designed South Africa's first app to warn residents of pollution levels, as Johannesburg suffers a spike in coal emissions in recent weeks, causing breathing problems and other health issues.

Africa's wealthiest city lies not far from the country's coal mines and the rotten-egg smell of sulphur has often been present in the air.

Environment Minister Willie Aucamp attributed the stink afflicting Johannesburg to hydrogen sulphide emissions from mining and industrial operations as far as 400 km east. 

"This (sulphurous smell) came from mines that exceeded their emissions," Aucamp told Reuters in an interview in Johannesburg.

"We don't know which specific mines yet. Investigations are still ongoing."

The app, launching later this year, uses data from hundreds of air-monitoring systems. It sends out notifications and advises residents on protective measures like wearing a mask during pollution surges, although masks only help with smog and soot, not gases like sulphur compounds.

SOME JOHANNESBURG RESIDENTS SUFFER BREATHING PROBLEMS
Coal employs tens of thousands of people, provides three quarters of South Africa's electricity and a quarter of its liquid fuels, converted from coal by Sasol.

Johannesburg resident Philasande Shange, who has asthma, said he developed a cough in February and March, which a health practitioner linked to the city's poor air quality.

"I couldn’t breathe or sleep, and I lost 15 kg," Shange told Reuters in an interview in Braamfontein.

Reuters interviewed five residents who reported flu-like symptoms, dizziness, sinus inflammation and asthma flare-ups.

AIR POLLUTION'S ECONOMIC COST UNDERCOUNTED, SAY ACTIVISTS   
Bruce Mellado, a researcher who pioneered the app, SACAQM (South African Consortium of Air Quality Monitoring), said their system had picked up a growing frequency of pollution spikes. 

South Africa's two biggest polluters, Sasol and state-owned utility Eskom, were granted extensions to emissions exemptions in 2025. Their largest facilities lie east of Johannesburg.     

Sasol spokesperson Alex Anderson said in an emailed response to questions that "no operational incidents or abnormal process conditions have been identified that would indicate an uncontrolled or atypical release" of sulfur emissions.

Eskom did not respond to a request for comment.

Authorities point to the need to balance environmental and economic imperatives when justifying lax air quality enforcement. Activists say that underestimates the economic cost of pollution-related disease.     

"We need more community monitoring (to) . . . understanding how much air pollution actually costs us," said Rico Euripidou, a campaign coordinator at GroundWork.