Seasonal variation and human exposure assessment of legacy and novel brominated flame retardants in PM in different microenvironments in Beijing, China.

Indoor exposure to legacy and novel brominated flame retardants (NBFRs) may cause potential risks to human health. Studies on seasonal variations of indoor PM-bound BFRs are scant. This study comprehensively investigated the seasonal variations of PM-bound polybrominated diphenyl ethers (PBDEs) and NBFRs in various indoor environments (i.e. activity room, dormitory, home and office) and outdoor PM in Beijing, China over one year. The levels of PBDE (226 ± 108 pg m) were higher than that of NBFRs (27.0 ± 16.0 pg m) in all indoor environments. Decabromodiphenyl ether (BDE-209) and decabromodiphenyl ethane (DBDPE) were the most abundant BFRs. Office showed the highest mean concentrations of ΣPBDEs (251 ± 125 pg m) and ΣNBFRs (33.0 ± 18.0 pg m), which may be related to the higher number density of indoor materials. The concentrations of ΣNBFRs and ΣPBDE in indoor PM were found to be significantly higher than those in the corresponding outdoor PM (p < 0.05). Two to twenty-fold seasonal variations were observed for levels of PM-bound BFRs during one year, and indoor concentrations increased slightly during the central-heating period (November 2016-March 2017). Seasonal variations of BFRs could be affected by temperature, relative humidity and concentrations of particle matters. The PM-bound BFRs concentrations in PM were negatively correlated with temperature and relative humidity, while positively correlated with PM concentrations (p < 0.05). Atmospheric haze pollution could possibly contribute to higher levels of indoor PM-bound BFRs. Human daily intake of BFRs via PM inhalation showed seasonal differences, and the highest exposure risk occurred in winter. Toddlers were assessed to be more vulnerable to indoor PM-bound BFRs in all seasons. This study provided the first-hand measurements of seasonal concentrations and human exposure to PM-bound BFRs in different indoor scenarios in Beijing.