Comparative Assessment of Atmospheric Pollutants Across Geopolitical Zones in Southern Nigeria Using Sentinel-5P (2019 and 2024)

Air quality across Southern Nigeria declined between 2019 and 2024, with distinct spatial and temporal variations in carbon monoxide (CO), nitrogen dioxide (NO₂), sulfur dioxide (SO₂), methane (CH₄), and aerosols. Using Sentinel-5P satellite data, pollution levels were mapped across the South-East, South-South, and South-West geopolitical zones. The South-West exhibited the highest overall pollutant concentrations, driven by vehicular emissions, industrial output, and extensive generator use, particularly in Lagos and Ogun states. The South-East recorded the steepest increases in CO, SO₂ and methane, linked to domestic energy reliance, population density, and widespread open waste burning. The South-South, despite intense oil and gas activity, showed comparatively lower mean pollutant values, likely mitigated by coastal ventilation, though localized hotspots in Benin city, Port Harcourt, Asaba and Warri remained severe. Between 2019 and 2024, methane and aerosol concentrations surged, with the South-West experiencing the sharpest rise in aerosol index. The data reveal a convergence in pollutant loads among zones by 2024, emphasizing the role of unregulated urban growth, fossil fuel dependence, and weak environmental governance. These findings emphasize rising regional air quality risks and the urgent need for differentiated policy strategies tailored to each zone’s socio-economic and environmental realities.