To evaluate the pollution level, congener distribution, and human exposure of polybrominated diphenyl ethers (PBDEs) in the atmosphere of Beijing''s office buildings, outdoor air samples (particles+gas) were collected from a typical scientific area and PBDEs concentrations were quantified using GC-MS. The results showed that the mass concentrations of PBDEs in the gas phase, PM_2.5, and PM₁₀ were 2.3-78.6 pg·m^-3, 14.4-335.3 pg·m^-3, and 11.6-431.7 pg·m^-3, respectively, and the annual average mass concentrations were 21.7 pg·m^-3, 96.9 pg·m^-3, and 149.3 pg·m^-3, respectively. BDE-209 was the predominant congener in particulates, accounting for 50% of the total concentration. The mass concentration of PBDEs in the particles decreased in the following order:autumn > winter > summer > spring, with an obvious change in winter and stability in summer. Tri-BDEs mainly existed in the gas phase, and the proportion of PBDEs in the particle phase increased with bromine number. Source analysis indicated that BDE-209 degradation was an important source of other PBDEs in the air. Exposure risk analysis showed that the respiratory intake of children and adults was 18.6 pg·(kg·d)^-1 and 7.1 pg·(kg·d)^-1, respectively, which is far below the recommended lowest observed adverse effect level of 1 mg·(kg·d)^-1. Similarly, the carcinogenic risk values of BDE-209 for children and adults were 2.3×10^-9 and 3.7×10^-9, respectively, which were much smaller than the carcinogenic risk limit of 10^-6, indicating that there was no health hazard from PBDEs in the atmosphere.