Atmospheric PM _2.5 and its trace element compositions in Bloemfontein, South Africa: an inhalation health risk assessment

Abstract

Fine particulate matter (PM_2.5) drives millions of global premature deaths via respiratory and systemic effects, exacerbated by bound trace elements. In South Africa, studies prioritize metros, overlooking midsized cities like Bloemfontein, where biomass burning, industry, and dust elevate pollution. The first age-stratified inhalation health risk assessment of PM_2.5 and trace elements in this setting was conducted using samples collected over 14 months (June 2020-August 2021) at Pelonomi Hospital and University of the Free State (UFS). Gravimetric analysis measured mass; and energy-dispersive X-ray fluorescence quantified trace elements from UFS samples. U. S. EPA methods assessed non-carcinogenic (hazard quotients, HQs) and carcinogenic risks (CRs) for infants, children, and adults. Annual PM_2.5 averaged 6 µ m^-3 at Pelonomi (12× WHO's 5 µg m^-3 guideline) and 11 µg m^-3 at UFS (2.2×). Vanadium (V) showed the highest non-carcinogenic risk across ages, and chromium (Cr) had a CR of 4.32 × 10^-5. V ranked Category A (priority), while Cl, Mn, Si, S, Cr, Ni, Fe, and Cu ranked Category B. Winter increased PM_2.5 concentrations and associated risks by 40%, underscoring regulatory shortfalls and the need for emission controls, clean energy transitions, and alignment of national standards with WHO guidelines to reduce pediatric risks (SDGs 3, 7, 11).