Tropospheric Assessment of Carbon Monoxide, Nitrogen Dioxide, and Aerosol in Port-Harcourt Metropolis, Rivers State, Southern Nigeria from 2019-2024

Air pollution is a global environmental concern, particularly in urban and industrialized areas. Consequently, the objective of this paper is to assess the levels of tropospheric carbon monoxide (CO), nitrogen dioxide (NO2), and aerosol in Port-Harcourt Metropolis, Rivers State, Southern Nigeria from 2019-2024 using the Sentinel-5 Precursor (Sentinel-5P) satellite data in Google Earth Engine (GEE) and other appropriate standard methods. The results revealed significant (P<0.05) temporal and spatial variations in pollutant concentrations, influenced by factors such as industrial activities, vehicular emissions, seasonal changes, and policy shifts, including the COVID-19 pandemic and fuel subsidy removal. CO levels peaked in the early months and declined in October across all years. NO₂ concentrations followed a consistent pattern, peaking in December and reducing during the rainy season, highlighting the impact of meteorological factors. Aerosol concentrations were highest in dry-season months (January and February) and lowest in the rainy season, with a sharp reduction during the 2020 lockdown. Spatial analysis showed that pollution hotspots were concentrated in industrial zones such as Trans-Amadi, Diobu, and Borokiri. The study highlights the effectiveness of remote sensing in monitoring air quality and provides critical data for policymakers to implement sustainable air management strategies. It also highlights the urgent need for stricter environmental regulations and cleaner energy alternatives to mitigate the adverse effects of air pollution on human health and the environment.