Emissions from the Road Traffic of West African Cities: Assessment of Vehicle Fleet and Fuel Consumption

Madina Doumbia,Siélé Silue,N’Datchoh Toure,Célestin Hauhouot,Véronique Yoboue,Arona Diedhiou

doi:10.3390/en11092300

Abstract

Traffic source emission inventories for the rapidly growing West African urban cities are necessary for better characterization of local vehicle emissions released into the atmosphere of these cities. This study is based on local field measurements in Yopougon (Abidjan, Côte d’Ivoire) in 2016; a site representative of anthropogenic activities in West African cities. The measurements provided data on vehicle type and age, traveling time, fuel type, and estimated amount of fuel consumption. The data revealed high traffic flow of personal cars on highways, boulevards, and backstreets, whereas high flows of intra-communal sedan taxis were observed on main and secondary roads. In addition, the highest daily fuel consumption value of 56 L·day−1 was recorded for heavy vehicles, while the lowest value of 15 L·day−1 was recorded for personal cars using gasoline. This study is important for the improvement of uncertainties related to the different databases used to estimate emissions either in national or international reports. This work provides useful information for future studies on urban air quality, climate, and health impact assessments in African cities. It may also be useful for policy makers to support implementation of emission reduction policies in West African cities.

Highlights

Air quality deterioration in West Africa is accentuated by an increase in urbanization across cities such as Abidjan (Côte d’Ivoire), Dakar (Sénégal), Lagos (Nigeria), Accra (Ghana), and Conakry (Guinea) associated with rapid population growth [1]
As there is no available database, the traffic data collected during the survey were validated using data provided by Bureau National d’Etudes Techniques et de Développement (BNETD), which is the national bureau of standards for monitoring and verification to support elaboration and implementation of development plans and policies in Côte d’Ivoire
Our measurements were made during the school season (February) while those of BNETD were collected during the holidays or non-school season (August)

Summary

Introduction

Air quality deterioration in West Africa is accentuated by an increase in urbanization across cities such as Abidjan (Côte d’Ivoire), Dakar (Sénégal), Lagos (Nigeria), Accra (Ghana), and Conakry (Guinea) associated with rapid population growth [1] This urbanization will lead to development into mega-cities by 2030 with an estimated population of 7.773 million for Abidjan, 6.046 million for Dakar, 24.239 million for Lagos, and 3.262 and 3.134 million for Accra and Conakry, respectively [2]. The car fleet of West African cities is mainly constituted of used vehicles from European and American countries [6,7,8]. These old vehicles often lack emission reduction technology [9,10]. Studies [15,16,17,18] in European areas and cities such as Naples, Sardinia, and in the Litorale Domizio-Agro Aversano, road traffic emissions were associated with uncertainties from emission factors (dependent on pollutant, vehicle type, inspection, and maintenance programs) as well as fuel consumption, driving patterns, and annual mileage

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