A new study claims that residents of central and southern Johannesburg face disproportionately high exposure to harmful vehicle emissions, with older vehicles and diesel-powered minibus taxis the biggest contributors to air pollution.
The report by The Real Urban Emissions (True) Initiative had researchers recording more than 250,000 vehicle exhaust measurements at 11 sites in Johannesburg between July 2025 and September 2025.
The findings show that a small proportion of older vehicles produced a disproportionately large share of emissions. Petrol passenger cars registered before 2006 accounted for just 4% of the fleet but were responsible for up to 24% of measured emissions of pollutants, including nitrogen oxides (NOx), hydrocarbons, carbon monoxide (CO) and particulate matter (PM).
Older petrol minibus taxis, representing 8% of the fleet, produced more than four times the average CO emissions of newer models, while diesel minibuses emitted up to 18 times more PM and 44 times more NOx than petrol equivalents.
The study also found that the latest diesel passenger cars and light commercial vehicles recorded average NOx emissions four to seven times higher than comparable vehicles in Europe.
Researchers estimate transport-related air pollution contributed to about 500 premature deaths and 200 new paediatric asthma cases in Johannesburg during 2024, rising to more than 1,200 premature deaths and nearly 500 asthma cases across Gauteng.
Central and southern Johannesburg were identified as pollution hotspots because of heavy reliance on public transport. Though minibus taxis made up only 10% of vehicles measured in these areas, they generated between 21% and 40% of total emissions.
The report recommends introducing Euro 6d/VI-D European regulatory vehicle emission standards for new vehicles to bring about significant emission reduction benefits and align South Africa with its major export markets.
South Africa’s fuel quality and mandatory vehicle emission standards lag well behind Europe’s Euro 6d/VI-D requirements. The country still relies mainly on 500ppm and 50ppm sulphur fuels, whereas Euro 6d-compliant vehicles require 10ppm sulphur fuel to operate as intended.
Euro 6d/VI-D vehicles require exhaust after-treatment devices that are prone to damage from the higher sulphur levels in current South African fuel. It is why carmakers frequently have to recalibrate engines or offer older engines locally compared with what they sell in Europe.
The government is targeting the introduction of the Clean Fuels 2 programme from July 2027, though the initiative has already been delayed several times since it was first announced more than a decade ago.
It aims to modernise South Africa’s fuel specifications and align them with international standards, but the programme has been repeatedly delayed because of the multibillion-rand investment required to upgrade the country’s ageing refineries.
The True report also recommends expanding vehicle inspection and maintenance programmes and encourages the adoption of electric minibus taxis through financial incentives.
City of Johannesburg officials said the report supports an existing recommendation by the city in June 2025 to use clean air zones as part of a transition to a cleaner transportation sector.
“The True Initiative has shown the shockingly high emissions of vehicles on Johannesburg’s streets,” said Sheila Watson, deputy director of the FIA Foundation, which established the True Initiative with the International Council on Clean Transportation.
“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 also to protect the health and lives of its residents.”
Business Day
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