Characterization of Particulate Matter, Gaseous Pollutants and Nine Heavy Metals in Ambient Air across Seven Sites in Adamawa State, Nigeria
Abstract
Ambient air pollution poses a significant public health threat in rapidly urbanizing sub-Saharan African cities, yet empirical data remain critically lacking for most Nigerian urban centres. Hence, the objective of this paper was to characterize total suspended particulate matter, size-fractionated PM (PM₁, PM₂.₅, PM₇, PM₁₀), gaseous co-pollutants (CO, CO₂), and nine heavy metals (Fe, Pb, Mn, Cr, Cd, V, Cu, Ni, Zn) across seven sites in Adamawa State, Nigeria using appropriate standard methods. Results obtained reveal that mean concentrations were: PM₂.₅: 14 µg/m³, PM₁₀: 78 µg/m³, TSP: 122 µg/m³, CO: 18.5 ppm, and CO₂: 3728 ppm. Maximum values reached critical levels: PM₂.₅: 120 µg/m³, PM₁₀: 635 µg/m³, TSP: 1560 µg/m³, and CO: 309 ppm. Heavy metal abundance followed the order: Cu> Zn > Fe > V > Cd > Ni > Pb = Mn > Cr. Copper and zinc classic tracers of brake wear and tyre debris were the most abundant anthropogenic metals, confirming non-exhaust traffic emissions dominate the heavy metal burden. Cadmium exhibited extreme spatial heterogeneity, indicating a localized point source. The low PM₂.₅/PM₁₀ ratio (0.18) indicates heavy metals are predominantly associated with coarse fugitive dust. Adamawa State in Nigeria faces a severe, multi-pollutant air quality crisis requiring immediate public health interventions.