Fig. 1: Composition profiles of OPEs and variation of OPEs as a function of PM2.5.

a Concentrations and relative contributions of alkyl-OPEs (i.e., TEP, TBEP, TEHP, and TPrP), aryl-OPEs (i.e., TPhP, TCP, and EHDPP), and halo-OPEs (i.e, TCEP, TCPP, TDCPP, and TDBPP) in gas phase and particle phase during summer and winter. Relationships between the mass concentrations of PM2.5 and ∑11OPEs in (b) gas phase and (c) particle phase in summer and winter. The square boxes and the error bars represent the mean values and standard deviation, respectively. The gray dots represent the concentration of total OPEs in the whole sampling period.