FAVOUR OSEMWONYENMWEN ELEGON

Aba, a major commercial hub in southeastern Nigeria, faces growing air pollution pressures, particularly from carbon monoxide (CO) and aerosols. Sentinel-5P satellite data processed on Google Earth Engine were used to track their concentrations from 2019 to 2024, with annual, monthly, and spatial patterns assessed alongside inter-annual variation. CO peaked at 0.0562 mol/m² in 2024 and was lowest in 2023 at 0.0489 mol/m². February consistently recorded the highest monthly values, reflecting intensified dry-season emissions and limited atmospheric dispersion. Aerosols followed a similar seasonal cycle, peaking in February, with the highest concentration in 2024 (0.1683) and the lowest in 2020 (-0.7115). Spatial analysis revealed persistent hotspots in central and northern Aba, especially around Ariaria International Market, Aba Industrial Zone, and Ngwa Road Market, while outlying areas such as Asa Umu Nka and Crystal Park Avenue maintained lower levels. Statistical testing showed that CO differences were significant in the early years (2019–2020, 2021–2022) and highly significant in the later period (2023–2024 and the 2019–2024 comparison), while no significant changes occurred in 2020–2021 or 2022–2023. Aerosols, by contrast, recorded highly significant differences from
2019 to 2022, but no significant changes in the later years, except for a strong 2019–2024
contrast. Despite these fluctuations, both pollutants remained persistently elevated in densely populated and economically active zones, underscoring continued risks to health and environmental quality. The findings confirm the value of Sentinel-5P and Google Earth Engine for urban air quality assessment and highlight the need for targeted emission control and stronger regulatory oversight.