A multi-technique appraisal of city-scale atmospheric pollution in Nigeria

Abstract

This thesis is motivated by the Earth’s environment taking serious hits, due to the propagation of varying atmospheric pollution across the cities of the globe. This propagation is driven mainly by the discharge of anthropogenic emissions such as; vehicular emissions, fossil fuel burning, industrial and biomass activities. Human exposure to alarming atmospheric pollution levels continues to be associated with a great number of adverse health effects. This challenge has resulted in air quality policymakers introducing globally adopted indices for air quality monitoring. The first task of this thesis was to review the existing air pollution status within the Nigerian territory. From the review of the available literature, the challenges were identified. A Nigerian city was adopted with the prospect of conducting a multi-technique appraisal of city-scale atmospheric pollution monitoring. Northern Nigeria’s educational hub, Zaria, was spatially and temporally analysed for the period of December 2015 – November 2016. Considering Nigeria’s limited technological resources, portable pollutant monitors were procured, validated and utilized for outdoor pollution measurement in this study. The results revealed alarming pollution levels, enough to rank Zaria amongst the World Health Organization’s list of polluted cities. With the alarming pollution level in Zaria, respiratory wellness from population exposure was assessed. Certified health markers revealed that outdoor pollution contributed significantly to the respiratory well-being of the studied population. Satellite datasets have been a distinctive means for air quality monitoring over developing countries like Nigeria with limited ground pollution information. Using collocating ground measurements, we appraised the city-scale suitability of multi-satellite pollution measurements. The performance indicators adopted revealed that the Measurements of Pollution in the Troposphere Carbon Monoxide (MOPITT CO) estimates and the Moderate Resolution Imaging Spectroradiometer aerosol optical depth (MODIS AOD), as the suited satellite measurements. Another fundamental issue of this study was to identify if the existing Nigerian Global Navigation Satellite System Reference Framework (NIGNET) could be utilized for aerosol/particulate monitoring. This was achieved by appraising the effect of atmospheric aerosol optical depth (AOD) and ground particulate matter (PM) on the NIGNET derived-precipitable water vapour (PWV). A dual-comparison of the PWV estimates showed a significant correlation between the GPS PWV and MODIS PWV estimates. Analysing the ground particulate datasets, MODIS AOD measurements and GPS derived precipitable water vapour (PWV) estimates, the result of the collocating datasets showed good agreement. The findings of this study contribute immensely to policies on efficient air pollution monitoring in Nigeria.