Health risk assessment and oxidative potential prediction based on atmospheric PM_2.5 and associated metals in metro...

Research on indoor air quality in metro stations has primarily focused on monitoring air pollutants and source apportionment, while potential health effects have received less attention. To address this gap, we collected PM_2.5 samples from platforms and concourses in five metro stations in Shanghai to assess health risks and develop a predictive model for atmospheric oxidative potential (OP). The study showed that the concentrations of PM_2.5 and metal compositions were higher on the platforms than in the concourses, but there was no significant difference between urban and suburban stations. Fe, Co, Cr, and Mn were substantially enriched in the metro environment, as indicated by concentration ratios among sampling sites. Further health risk assessment of these enriched elements revealed that the hazard quotient (HQ) for Mn and the excess lifetime cancer risks (ELCRs) for Co and Cr were elevated, suggesting that these three elements should be prioritized in indoor air quality management. The atmospheric OP on the platforms was higher than that in the concourses, consistent with the distribution of PM_2.5 concentrations. Spearman correlation analysis demonstrated that Mn, Fe, and Co were strongly positively correlated with OP. A multiple linear regression model developed to predict atmospheric OP revealed that Mn concentration was an effective predictor of atmospheric OP in metro stations (adj. R² = 0.795). Our results provided essential references for controlling and predicting air pollutants in metro stations.