Comprehensive assessment of PM2.5 exposures around a regional mining site in India: integrating chemical composition, oxidative potential and health risk
摘要
Fine particulate matter (PM2.5) is pervasive in the atmosphere, particularly in densely populated industrial areas with multiple fugitive emission sources, such as opencast coal mining regions. Open-cast coal mining operations generate substantial particulate matter pollution, raising environmental and health concerns in the areas surrounding the mines. While PM2.5 levels are routinely regulated in mining regions, the chemical composition and toxicity of PM2.5, which may substantially influence health risks remain inadequately characterized. In this study, the composition, toxicity, and health risk of PM2.5 at six locations (two roadsides, three residential sites, and one residential background site) around an active opencast coal mining area in eastern Maharashtra, India were investigated. PM2.5-bound elemental carbon (EC), organic carbon (OC), metals, trace metals, polycyclic aromatic hydrocarbons (PAHs), and oxidative potential (OP) were examined. Highest PM2.5 levels were found at the roadsides (~ 400 µg m−3) and at 2 and 5 km from the mine (122 ± 43.4 µg m−3and 116 ± 35.5 µg m−3, respectively). Carbonaceous species and metals comprised ~ 40–50% of PM2.5 mass with Cr, Ni, Fe, Mg, and Zn nearly five-ten folds higher at the roadsides and residential sites closest to the mine compared to the background and the 10 km residential site. EC exhibited a high cancer risk (10–3), suggesting a serious health burden. Toxicity of PM, measured as OPvAA and OPvDTT, was higher at the roadside (18.05 ± 15.54 nmol min−1 m−3 and ~ 8.15 ± 9.94 nmol min−1 m−3), respectively, driven by metals and organics (r = 0.3–0.5, p < 0.05). Benzo(a)pyrene and naphthalene dominated the PAHs fraction having 5–tenfold higher concentrations than other PAHs. Multivariate regression model explained 25–40% of the variability in OPvAA and OPvDTT, primarily affected by Fe, Cr, Zn and EC. Overall, communities residing near active opencast coal mines experienced elevated exposure to PM2.5-bound chemical components, resulting in substantial toxicity and health risks. These findings demonstrate the value of integrating chemical composition, oxidative potential, and health risk assessment to better characterize PM2.5-linked health risks and burdens in communities impacted by mining and industrial sources. This bridges a significant gap in current air quality and health risk studies and provides evidence to inform future policy and regulatory decisions.