Particle size distributions and gas-particle partitioning of polychlorinated dibenzo-p-dioxins and dibenzofurans in ambient air during haze days and normal days

Little information is available on the distributions of airborne polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) during haze days. In this study, PCDD/F concentrations, particle size distributions, and gas-particle partitioning in a Beijing suburban area during haze days and normal days were investigated. High PCDD/F concentrations, 3979-74,702 fg m(-3) (173-3885 fg I-TEQ m(-3)), were found during haze days and-98% of the PCDD/Fs were associated with particles. Most PCDD/F congeners (>90%) were associated with particles. PCDD/ F concentrations increased as particle sizes decreased and 95% of the particle-bound PCDD/Fs were associated with inhalable fine particles with aerodynamic diameters < 2.5 mu m. PCDD/Fs were mainly absorbed in the particles and the Hamer-Bidleman model predicted the particulate fractions of the PCDD/F congeners in the air samples well. The investigated PCDD/F concentrations and particle-bound distributions were different during normal days than during haze days. Temporal airborne PCDD/F trends in a suburban area during haze conditions could support better understanding of the exposure risk posed by toxic PCDD/Fs associated with fine particles. (C) 2016 Elsevier B.V. All rights reserved.