Differences in the seasonal variation of brominated and phosphorus flame retardants in office dust

This study documents the temporal variability in concentrations of flame retardants (FRs) in floor dust from three offices in Beijing, China. Dust from Office A (OAD) was collected weekly from March to August, 2012, and sampling of dust from Office B and C (OBD and OCD) was conducted fortnightly (each two weeks) from March to December 2012. With intensive and continuous sampling, we report for the first time on clear and coherent temporal trends of polybrominated diphenyl ethers (PBDEs), novel brominated flame retardants (NBFRs) and phosphorus flame retardants (PFRs) in indoor dust. The observed mean concentrations of ∑9PBDEs, ∑4NBFRs and ∑9PFRs, were 554, 11,100 and 128,000ngg(-1) in OAD; 7560, 5000 and 17,300ngg(-1) in OBD; and 4750, 3550 and 17,200ngg(-1) in OCD, respectively. With exception of PBDEs, concentrations of FRs were elevated in OAD than in OBD and OCD. Two to ten-fold variations were observed between the minimum and maximum concentrations of FRs in the same office, indicating that the sampling moment exerts a substantial influence on the level of FR contamination. Different seasonality was distinctively found between BFRs and PFRs. Except for a few occasional abnormal values, BFR levels in office dust were generally constant among different seasons. The abundance rank order for PFRs was: winter>autumn>summer, with peak values occurring in late winter and early spring. This pattern may be attributable to the fact that PFRs are more sensitive to temperature changes compared to PBDEs and NBFRs owning to their higher volatilities. The absence of significant seasonal variation for BFR concentrations in indoor dust compared to outdoor air and dust concentrations is also discussed.