A new report compiled by global partnership The Real World Urban Emissions (TRUE) Initiative reveals unequal exposure to vehicle emissions and air pollution across Johannesburg.

The report was compiled by independent nonprofit research organisation International Council on Clean Transportation (ICCT) researchers Mallery Crowe, Kaylin Lee and Yoann Bernard, in collaboration with the City of Johannesburg, the University of Johannesburg Energy and Environmental Technology Station (UJ PEETS) and global climate and public health initiative Breathe Cities.

This initiative conducted its first real-world roadside remote sensing campaign in Africa, collecting more than 250 000 vehicle exhaust measurements in Johannesburg to provide a comprehensive picture of emissions from light- and heavy-duty vehicles across the region.

Petrol passenger cars registered before 2006 made up 4% of the fleet but contributed up to 24% of the fleet’s measured emissions, including nitrogen oxides, hydrocarbon, carbon monoxide and particulate matter.

Between July and September 2025, remote sensing technology situated at 11 different sites throughout the city captured the fleet’s emissions.

The researchers say transportation related emissions contributed to about 500 premature deaths and 200 new pediatric asthma cases within Johannesburg, and over 1 200 premature deaths and about 500 new pediatric asthma cases across the province.

This study also reveals that, in 2024 alone, residents of central and southern Johannesburg, who depend most heavily on public transit, faced the highest vehicle emission exposure in the city.

In these areas, minibus taxis accounted for 10% of the measured fleet, yet contributed 21% to 40% of total emissions, with particularly elevated carbon monoxide and hydrocarbon emissions.

The oldest vehicles, representing a small portion of the overall fleet, showed the highest measured emissions.

Petrol passenger cars registered before 2006 contributed between 12 and 24% of the fleet’s total 12% of total nitrogen oxide emissions, 21% of hydrocarbon, 22% of carbon monoxide, and 24% of particulate matter emissions, while petrol-powered minibus taxis, also registered before 2006, contributed 22% to 25% to the fleet’s total hydrocarbon and carbon monoxide emissions.

Diesel-powered minibuses exhibited particulate matter and nitrogen oxide emissions up to 18 and 44 times higher, respectively, than their petrol counterparts.

The increasing popularity of these diesel-powered vehicles, which accounted for 98% of all new minibus taxi registrations in 2025, up from 7% in 2001, could carry significant health impacts for residents if left unchecked, the TRUE Initiative highlights.

“This latest testing campaign has expanded our picture of vehicle emissions in Johannesburg and can help broaden our understanding of vehicle emissions across the larger region in Africa.

“We see that a small number of older vehicles emit a disproportionate amount, so targeted policies to quicken fleet turnover will be crucial to improve air quality,” Crowe says.

Breathe Cities South Africa portfolio manager Nokuthula Dubazane says the findings provide the evidence needed to support targeted air quality interventions and inform policymaking

“This report gives Johannesburg the evidence it needs to act. The city has already proposed clean air zones as a key policy solution, and findings like these, showing exactly where emissions are highest and who bears the greatest burden, are what turn recommendations into targeted, effective policy.

“At Breathe Cities, we believe cleaner air is achievable when cities have robust data to make informed decisions, and we hope this study accelerates that process in Johannesburg and across the continent,” Dubazane adds.

To reduce vehicle emissions, the TRUE Initiative has recommended the adoption of European regulatory standards for new vehicles, expanding and enforcing Johannesburg’s existing vehicle inspection and maintenance programme and the adoption of electric minibus taxis to reduce emissions and lifetime operating costs for owners, accomplished through financing schemes to reduce upfront costs.

Summarising the significance of the findings, Federation International del’Automobile (FIA) Foundation deputy director Sheila Watson says the results underscore the urgent need to tackle vehicle emissions as a public health priority.

“The TRUE Initiative has shown the shockingly high emissions of vehicles on Johannesburg’s streets. Hundreds of the city’s residents are sicker or dying each year because of dirty air, to which road vehicles are a major contributing factor.

“Real-world data such as this in Johannesburg is vital to understand, and then address a public health crisis. These findings point to the need for urgent action, not only to clean up the city’s air but to protect the health and lives of its residents,” Watson concludes.