Gas-particle partitioning and health risk estimation of polycyclic aromatic hydrocarbons (PAHs) at urban, suburban and tunnel atmospheres: Use of measured EC and OC in model calculations

Abstract

Gas and particle phase ambient concentrations polycyclic aromatic hydrocarbons (Sigma 13PAH) were determined at urban and suburban sites in Eskisehir and in a traffic-tunnel. Organic and elemental carbon (OC and EC) concentrations of total suspended particles (TSP) were also measured. Atmospheric Sigma 13PAH (gas+particle) concentrations measured at suburban sites was found to be lower than that of tunnel and urban site. Concentrations of TSP and OC/EC were highest in the tunnel. Fluorene, Phe, Flt and Pyr were the most dominant PAH compounds in gas phase samples for all three sampling locations, while BaA, Chr, BbF, BkF and BaP were found to be higher in particle phase. Gas-particle partitioning coefficients, (Kp) and particle-phase fractions (Phi) of PAHs were correlated with supercooled vapor pressures (P-L(o)). Non-linear curve fitting of Phi versus log P-L(o) was found to be more robust than linear logarithmic regressions of log Kp versus log P-L(o). Kp of PAHs were estimated by octanol-air and soot-air partitioning models and the results were compared with the experimental Kp values. Measured EC and OC concentrations were used in model calculations. Use of measured carbon concentrations in model calculations resulted much better estimations for tunnel samples. Gas-particle partitioning of PAHs for the majority of the compounds were controlled by adsorption onto soot carbon and adsorption into the organic matter. Cancer risks associated with inhalation and dermal contact were also estimated. Generally, the estimated cancer risks were below 1 x 10(-5) for urban and suburban sampling locations.