Particulate Matter Chemical Speciation, Source Apportionment, and Health Impact Assessment in Northern Nigerian Cities

This dissertation advances the scientific understanding of particulate matter pollution in Northern Nigerian cities through original chemical speciation, source apportionment, and health impact assessment research in Kano, Kaduna, and Maiduguri, filling a major gap in the air quality science literature for the African Sahel region. Fine and coarse particulate matter in Northern Nigerian cities arises from a complex mixture of mineral dust entrained from the Sahara by Harmattan winds, vehicle and generator combustion emissions, biomass burning, and industrial sources, but the quantitative contribution of each source type and the specific chemical composition driving health effects have not been characterised. Particulate matter sampling at high-volume samplers at urban receptor sites over twenty-four months provides PM2.5 and PM10 filter samples that are subjected to comprehensive chemical analysis including water-soluble ions, carbon fractions, major elements, and trace metals by ion chromatography, thermo-optical transmittance, and X-ray fluorescence. Receptor modelling using positive matrix factorisation and chemical mass balance methods is applied to apportion measured concentrations to source categories. Health impact assessment applies the Global Burden of Disease concentration-response relationships to estimate attributable mortality and morbidity from measured PM2.5 concentrations. Original contributions include the first comprehensive chemical speciation dataset for Northern Nigerian urban aerosol, a seasonally resolved source apportionment that quantifies the Harmattan dust contribution against combustion sources across the three cities, and a health burden calculation disaggregated by source type. The dissertation provides the evidence foundation for targeted air quality management in Northern Nigerian cities. Keywords: particulate matter, source apportionment, chemical speciation, health impact, Northern Nigeria.