Air Quality in African Cities

Abstract

Air pollution has become a major environmental issue in African cities during the last decade. Rapid urbanization, traffic congestion combined with old cars and low quality fuel, open-burning of waste and biomass, dust and sandstorms are the major sources of air pollution. These anthropogenic and natural sources are responsible for emissions of particulate matter (PM), Nitrogen dioxide (NO2), Carbon monoxide (CO), sulphur dioxide (SO2), Volatile Organic Compounds (VOCs) that can affect human health. The comparative analysis of urban air pollution in Africa shows that very few cities measure air quality in Africa. In sub-Saharan Africa region, only South Africa and Senegal have setup continuous air quality monitoring system. Some other countries such as Nigeria and Ghana conducted air quality monitoring programs in 2011 and 2004 respectively. In the 2016 WHO urban air pollution database, 41 cities of 12 sub-Saharan African countries reported their data. The analysis shows that all these cities exceed the WHO guidelines for PM10 and PM2.5 annual concentrations. A case study for Dakar (Senegal) presents the distribution of the air quality measurement network around the city, the monitored pollutants and the Air Quality Index (AQI) that daily informs people and decision markers about the air quality. The AQI is unhealthy (orange) to very unhealthy (red) during the dry season (mid-November to April). During the rainy season (June to October), the AQI is good (green) to moderate (yellow). Air pollution in Dakar is mainly due to particulate matter (PM10 and PM2.5). Annual mean of these PM exceeded WHO guidelines from 2010 to 2017. To tackle air pollution, regulations and measures are taken by Senegalese authorities to reduce emission from transport, industries and energy. For the transport sector, renewal of old cars and promoting of mass transport are the major projects. For other sources (industry, waste and energy), environmental law provides for preventive measures and energy efficiency programs are on-going.