Elemental Composition, Sources, and Health Risks of Ambient PM2.5 in Ust-Kamenogorsk (Oskemen) and Pavlodar, Kazakhstan

Atmospheric pollution by fine particulate matter (PM2.5) poses a severe threat to public health in industrial regions of Kazakhstan, such as Ust-Kamenogorsk and Pavlodar, where a sharp continental climate exacerbates toxic element accumulation. This study aimed to compare the elemental composition of PM2.5 in Ust-Kamenogorsk and Pavlodar using ICP-OES (FPI EXPEC-6500) and ICP-MS (FPI SUPEC-7000), identify key pollution sources through chemometric approaches, and quantitatively evaluate inhalation health risks for adult and pediatric populations. Principal component analysis (PCA) revealed contrasting emission profiles: Ust-Kamenogorsk was dominated by non-ferrous metallurgical signatures, whereas Pavlodar was driven by high-ash coal fly ash from thermal power plants, ferrous metallurgy, and petrochemical operations. Non-carcinogenic health risks were exceptionally high in both cities, with cumulative hazard indices exceeding the safe benchmark (HI = 1.0) by over 500-fold, predominantly driven by extreme contributions of Zn (HQinh = 304.7) and Al (HQinh = 129.5). Carcinogenic risks for adults were governed by Cr and As, reaching 8.7·10−4 and 4.1·10−4 in Ust-Kamenogorsk, and 4.4·10−4 and 5.0·10−4 in Pavlodar, respectively—exceeding the maximum acceptable threshold (1·10−4) by up to 9-fold. For children, Cr presented an elevated risk (1.7·10−4) in Ust-Kamenogorsk, while borderline values were observed in Pavlodar.