Characterization of PM2.5-bound PAHs in indoor and outdoor air of an office in winter period

Abstract

The mass concentrations of indoor (a naturally ventilated office) and outdoor (adjacent courtyard) PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) were investigated from December 14 to December 30, 2015 in Xi’an, China. Sixteen PM2.5 samples were collected on quartz filters with 47 mm diameter and analyzed. The results indicated that the average mass concentrations of PM2.5 and total 16 PAHs in indoor and outdoor environments were 90 µg/m3, 374 ng/m3 and 105 µg/m3, 473 ng/m3, respectively. The dominant individual PM2.5-bound PAHs were BbF, BaP, IcdP, Chr, BghiP, and BkF in indoor environment, whereas the most abundant outdoor PAHs were BbF, Chr, BaP, BaA, Flu, and Pyr. A majority of I/O ratios of individual PAHs were lower than 1 indicating mostly the contribution of outdoor sources rather than the indoor ones. Diagnostic ratios of PAHs showed vehicle emissions, biomass and coal combustion might be the primary sources of indoor and outdoor PM2.5-bound PAHs. The calculated equivalent toxicity concentrations and excess cancer risk (ECR) were all over the acceptable level, meaning that people working in the office had a greater inhalation cancer risk due to PAHs exposure.