资源环境科技发展态势分析平台

As rush hour dawns in Dar es Salaam, brightly coloured bajaji – or gas-powered rickshaws – deftly and opportunely squeeze through gaps between packed minibus taxis, known as dala dala.

Nearly half of the Tanzanian city’s 6.4 million residents rely on these vehicles, as well as a small bus rapid transit (BRT) fleet, as their primary mode of transportation. As these vehicles inch through congested streets and crowded urban spaces, they emit trails of soot that pose serious health risks to commuters and city dwellers. With urban populations in Africa set to increase by 2 billion people by 2050, experts say the problem will only get worse.

Through decarbonizing the transport sector and transitioning to cleaner buses, African cities can reduce environmental damage and human health risks while delivering a more reliable and speedy transport system to their growing urban populations, say experts.

The United Nations Environment Programme (UNEP) is helping African cities drive towards soot-free public transportation, including electric-powered buses. Building upon its successful campaign to eliminate leaded petrol and reduce sulfur levels in diesel fuels, UNEP has been developing strategic roadmaps and conducting readiness assessments to establish the groundwork for a low-carbon future for public transportation.

“Buses and trucks are a big source of harmful small particulate matter and black carbon, which is the second-most important short-lived climate pollutant,” says Jane Akumu, UNEP Programme Officer in the Sustainable Mobility Unit. “Vehicle fleets in a lot of the African cities are doubling every 10 years, so you can imagine the situation now – which is already bad – will get worse without action.

“Soot-free buses, low-sulfur fuels and cleaner vehicle technologies are the target because they would significantly reduce harmful emissions.”

Hazard warning

Approximately 95 per cent of the world's transport energy still comes from fossil fuels. Sulfur levels in these fuels – particularly in diesel – mean that they form harmful particulate matter when burned, including black carbon, known as soot.

The health risks are stark.  Air pollution causes one in nine deaths, and nine out of 10 people breathe unclean air, according to the UNEP Pollution Dashboard. Burning fossil fuels also produces carbon dioxide, the main greenhouse gas that contributes to global warming and, in extension, myriad changes in our climate and natural systems.

Research shows that if humanity does not halve annual greenhouse gas emissions by 2030, it will be very difficult to limit global warming to 1.5 °C compared to pre-industrial levels by the end of the century. Based on current unconditional pledges to reduce emissions, the world is on a path to see global warming of 2.7 °C by the end of the century compared to pre-industrial levels.

Changing lanes

Many African cities’ formal public transportation systems have been unable to match the rapid growth of urban populations, ushering in a market for informal competitors, which eventually form the sector’s fabric.

“Public transport has failed… so people are now moving to two-wheelers, three-wheelers because they are more convenient and faster,” says Akumu. “It's highly polluting.”

It is also not safe, says Akumu, noting that two- and three-wheelers account for many of the accidents in African cities.

In November 2021, UNEP, the Climate and Clean Air Coalition  (CCAC)and the African Association of Public Transport (UATP) held a workshop and launched key guidelines that establish a strategic roadmap designed to help African cities embrace electric mobility.

Response has been largely positive, according to the UATP, an association that works with governments on the development of public transport across 13 African countries.

“Governments in sub-Saharan Africa are receptive and fully support the transition to soot-free buses,” says Yssoufou Cisse, UATP Secretary General.