Authors
Egide Kalisa, Tom Harner, Franck Kwabe, Amandeep Saini, Jacob Mastin
Published in
Environmental pollution (Barking, Essex : 1987). Pages 129361. Oct 17, 2026. Epub Oct 17, 2026.
Abstract
Air pollution in sub-Saharan Africa remains poorly characterized, particularly for chemically resolved organic and metal pollutants. We measured 23 polycyclic aromatic hydrocarbons (PAHs) and 24 trace metals (acid-digested fractions for total metals present and water-soluble fractions) at 10 sites across five East African countries using polyurethane foam passive air samplers (PUF-PASs), with dry-season sampling at all sites and paired wet-season sampling at four. The 30-day integrated dry-season samples revealed spatial heterogeneity in both pollutant concentrations and compositions. PAH profiles varied markedly among sites in the relative contributions of 2-to 6-ring compounds, and water-soluble metals generally accounted for only a small fraction of total metal concentrations. Enrichment factors distinguished crustal-associated elements from relatively enriched ones. Source characterization, combining PAH diagnostic ratios, the HYSPLIT trajectory model, Spearman correlation, and principal component analysis (PCA), indicated mixed, overlapping source influences rather than single-source signatures. Over 90% of air masses at all sites arrived from the south and south-east, and neighbouring cross-border sites received nearly identical air, indicating that local rather than long-range sources drove the concentration differences. In the compound-level PCA, the first two components explained 46.5% and 19.9% of the total variance, and several PAHs and metals shared similar spatial co-loading patterns. PAH and metal concentrations were generally lower in the wet season at four paired sites. Screening-level health-risk estimates varied widely across sites: metal-associated risk dominated at some high-metal sites, while PAH-associated risk was highest at Bukavu. These estimates represent screening scenarios, not measured lifetime risks. This study demonstrates the feasibility of effectively addressing critical monitoring gaps by using PUF-PASs, which are simple, electricity-free passive samplers for characterizing complex pollutant mixtures in data-sparse East African settings and provide time-integrated samples over weeks/months. The study provides an initial regional reference dataset to inform expanded long-term monitoring and air-quality management.
PMID:
42892516
Bibliographic data and abstract were imported from PubMed on 18 Oct 2026.
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