Afrique Sub-Saharienne
Clean Air Initiative: GlobalClean Air Initiative: AsiaIniciativa del Aire Limpio: América LatinaClean Air Initiative: Sub-Saharan Africa
Advanced Search
Dialogue room
Mailing List
Vehicular air pollution
High rate of urbanization (4% to 8% in a number of cities) expected to be sustained for the next decade, combined with low-income solutions to daily commuting, has resulted in the rapid increase in pollutants emitted by motorized vehicles.

As Sub-Saharan African cities experience increased urbanization and motorization, air pollution, particularly from vehicles still using leaded gasoline, is worsening. By providing access to business and public facilities, urban transport plays a critical role in the development of urban areas and overall economic growth but it also generates a number of externalities in terms of accidents, noise, traffic congestion, and air pollution. The latter is becoming a major environmental and health concern in sub-Saharan Africa. High rate of urbanization (4% to 8% in a number of cities) expected to be sustained for the next decade, combined with low-income solutions to daily commuting, has resulted in the rapid increase in pollutants emitted by motorized vehicles. Low income levels have been an incentive to import older used vehicles in recent years, to use cheap two-wheelers and cheap fuel, and to postpone vehicle maintenance.

Such conditions multiply many times the emissions per kilometer traveled, as do slow speeds due to low investment in road maintenance and traffic management. Roadway conditions are poor, vehicles are not inspected, fuel quality is low, and public transportation is undersupplied and unaffordable for many residents. Walking is still a major transportation mode in African cities, exposing the poorest to hours of breathing highly polluted air. Forty percent of urban trips are made on foot and sidewalks are often missing or in disrepair. The many roadside vendors, mostly women, are exposed throughout the day.

  • Lead

The most harmful of pollutants that are contained in vehicle emissions is the lead added to gasoline. The serious health impacts of lead have been extensively researched and documented and are well understood. Lead is an insidious and slow-acting poison that is easily absorbed and remains in the body.

When people breathe in airborne lead from emissions, it accumulates in the body tissues and leads to anemia, hypertension, and permanent loss of brain function, particularly in infants and children. Exposure to lead has been shown to reduce intelligence quotients in children by 2-3 points for every additional 100 micrograms/liter of lead in children's blood. Children are at greatest risk, especially very young children, because their digestive systems absorb lead much more readily than adults, and it accumulates in the soil upon which they play and which gets on their clothes and toys. The result is not only illness but permanently stunted mental capacity. Poor children are most at risk because malnutrition intensifies lead absorption.

Among adults, lead causes elevated blood pressure, cardiovascular conditions, neurological and kidney-related diseases. Adults lose productivity and die earlier because of air-borne toxins.

Recommended World Health Organization (WHO) air quality guideline for lead (Pb) content in the air is low, as exposure to even small amounts can be harmful:

WHO air quality guideline for lead: 0.5 µg Pb/m3, as an annual average

Africa and the Middle East are among the last regions where motorized vehicles continue to use almost exclusively leaded gasoline. In 1993, motor vehicles in Africa emitted over 13 million tons of lead, or almost a quarter of the global annual lead emissions of 60 million tons.
Experience worldwide has demonstrated that switching to unleaded gasoline is practicable, technically feasible, cost-beneficial, and can be done quickly, in both developed and developing countries. As a result, many countries around the world have eliminated lead additives from gasoline, and over 80 percent of gasoline sold worldwide is now unleaded, Africa remains one of the exception.

The elimination of lead from gasoline has been identified as a priority, not only because of the harmful content of lead, but also because of the triggering effect that this would have on pollution. The use of unleaded gas is a prerequisite to introducing catalytic converters which, in turn, can help reduce pollutants by as much as 90 percent.

Switching quickly to unleaded gasoline will be a first step toward reducing air pollution in Africa and thereby improving the health and quality of life for millions throughout the continent. It is one of the most cost-effective steps to protect children's health.

  • Respiratory & Blood Toxins

The three next most harmful pollutants from fuels which affect the respiratory system are: sulfur dioxide (SO2) which irritates the lungs and increases the frequency of lung and bronchial infections, nitrogen oxides (NOx) which tend to increase respiratory symptoms and decrease lung function, and suspended small particulates (SPM) less than 10mm diameter (PM10) which pass through the filter of the larynx and accumulate in the lungs. These three pollutants are those produced in greatest quantities by the combustion of diesel fuel.

Recommended WHO air quality guidelines for these three pollutant content are also low, as prolonged exposure to even small amounts can be harmful.

WHO air quality guideline for carbon monoxide (CO) content is much higher, but CO is also produced at a much higher level when gas is burned. Although the carbon monoxide's effect can be temporary, it is potentially lethal as it replaces oxygen in the bloodstream.

Hydrocarbons (HC) consist of a mixture of pollutants and contain benzenes, which are known carcinogens and can, in high doses, damage the production of blood cells. These pollutant emissions are lower in diesel fuel than in gasoline fuel.

These various pollutant emissions depend on the daily kilometers traveled, the fuel composition, the age of the vehicle fleet, and also the composition of the fleet.

For instance, pilot studies conducted in Dakar and Ouagadougou, under the Clean Air Initiative in SSA, show that as a result of the higher use of public buses and an old fleet of private cars in Dakar, the majority of which are diesel vehicles, the emissions of NOX, SO2 and PM10 are higher than in Ouagadougou. While in Ouagadougou, the high number of mopeds, their high usage (more daily travels), and the fuel they use (over-mixture of lubricant oil with gasoline-8% of oil instead of 4%) result in 1.3 times more CO emissions and 6 times more HC emissions than in Dakar.

Urban air pollution patterns may vary from one city to another depending on these various factors, and pollutants need to be identified and quantified according to their potential sources. Although the trends and sources of transport air pollution may somewhat vary between cities, the results are the same: health problems mostly for children and the poorest, reduction in productivity, poorer quality of life, and degradation of the environment.

Currently about 85 percent of all gasoline sold in the world is unleaded. This leaves only about 15 percent leaded fuel, sold and used mainly in Africa, parts of Asia, and Eastern Europe. In many of these countries, there is still a poor understanding of the risks of lead exposure and confusion about the technical difficulty of eliminating leaded gasoline.

Levels of lead in gasoline sold in SSA in 1990-93 ranged from around 0.4 mg/l to twice that level, and according to an IPEICA survey about 85 percent of gasoline sold in SSA (in 1998) was leaded. This is about on a par with Central Asia, India and Pakistan, where phase-out of leaded gasoline is also underway with a target date of 2005. In contrast, 100 percent of gasoline in North Africa and 90 percent in China is leaded, while on the other end of the spectrum, the US, EU, and Central America are lead-free zones.

A profile of the gasoline supply in each of the five sub-regions of SSA is provided below.

Key features of the gasoline supply in SSA:

Sub-Regions In SSA Key Features of Gasoline Supply Key Refinery Centers
East Africa

- Gasoline sold in sub-region has high levels
of lead (0.4-0.8 g/l).
- Single grade of gasoline available.

Nigeria and Neighboring Countries

- Nigeria produces 1/3 of total SSA gasoline
output. Due to its heavy subsidizing and high
quality, smuggling of Nigerian gasoline is
a major source of supply in SSA and the neighboring countries.
- Planned lead level reduction to 0.15 g/l by
the end of 2002.
- Single grade of gasoline available.
- Unleaded gasoline available at Port Harcourt refineries.

Southern Africa

- South Africa produces 1/3 of total SSA
gasoline output.
- Unleaded gasoline available in Botswana, Mozambique, Namibia, South Africa and

Angola, South Africa
West Africa

- Gasoline sold in sub-region has high levels
of lead (0.4-0.8 g/l), excepted for the TOR
refinery of Ghana which plans to reduce lead
content to 0.14 g/l by 2002.

Côte d'Ivoire, Ghana, Senegal
West Central Africa

- Gasoline sold in sub-region has low levels
of lead (0.20-0.60 g/l)
- Single grade of gasoline available.

Cameroon, Gabon, Congo (Kinshasa)

Rapid phase-out of leaded gasoline in SSA can begin with import policy changes in countries that import all of their gasoline, such as Tanzania, Ethiopia, Djibouti, Mauritania, Mozambique, as they can convert most quickly. However, major producer countries, such as Nigeria, Kenya, South Africa, that supply other countries must take the lead in phasing out the production of leaded gasoline.

Switchover to distribution of unleaded gasoline will be hardest and most expensive in countries where only one grade of gasoline is sold, as in Nigeria and its neighbors and Central and East Africa sub-regions. Where more than one grade of gas is sold, it is easy to add an additional, unleaded grade of gasoline, particularly in countries that depend entirely on imported gasoline. Only a few countries satisfy both of these conditions, including Niger, Mali, Mauritania, and Tanzania.

Gasoline smuggling is a major source of supply in SSA, particularly in the countries bordering on Nigeria because prices of gas in Nigeria are heavily subsidized and fuel quality is higher. In Benin, 80 percent of distribution of petroleum products is in the hands of the informal sector that is supplied mainly through smuggling.

In developing transport emission control and prevention programs for cities, an effort must be made to build on existing measures in Sub-Saharan cities, and to learn from the experiences of other countries. In addition, the private sector has to be closely involved in the programs to reduce transport emissions in cities.

The Clean Air Initiative partners in collaboration with the Institute for Energy and Environmental Research (IFEU) is currently developing an Information Pool with comprehensive information on cleaner vehicle/fuels technologies for urban buses and trucks.

Cleaner vehicles
Cleaner fuels and energy sources
Transportation and traffic management
Non-motorized transport
Documents available for download
Measuring impacts
Policies and instruments
Vehicular air pollution
Education and awareness

Tel: +1 (202) 458-0859 / Fax: +1 (202) 676-0977/8 / E-Mail: [email protected]