Towards Sustainable Air Quality in Coal-Heated Cities: A Case Study from Astana, Kazakhstan

Despite severe particulate matter (PM) pollution in Central Asia, limited air composition and health impact data are hindering sustainable air quality management and resilient urban planning. This study provides the first comprehensive assessment of PM_2.5 and PM_2.5–10 in the urban environment of Astana, Kazakhstan, a rapidly expanding city with intense winter heating demands. We characterized PM and atmospheric precipitation and assessed health risks using bioaccessible fractions of PM-bound potentially toxic elements (PTEs). Among 388 samples, PM_2.5 and PM_2.5–10 concentrations peaked at 534 and 1564 μg·m⁻³, respectively. Scanning electron microscopy (SEM) identified soot and coal fly ash, indicating fossil fuel combustion as a major source. Precipitation characterization also showed elevated SO₄²⁻ (17.8 μg⋅L⁻¹), V (108 μg⋅L⁻¹), Ni (84.0 μg⋅L⁻¹), and Mn (63.2 μg⋅L⁻¹). Bioaccessibility tests showed high solubility for Fe (16,229 mg·kg⁻¹) followed by V: key indicators of combustion emissions. Non-carcinogenic risk for Ni and V exceeded acceptable limits for adults and children (e.g., HQ: 6.07 for V for adults). Carcinogenic risk exceeded the threshold 10⁻⁶ for Cd (adults), Co, Cr, and Ni. These findings may help advance urban air quality management via integrating bioaccessibility-based health risk assessment and source apportionment, supporting evidence-driven policies for environmentally responsible development in rapidly urbanizing cold-climate regions.