[Pollution Characteristics of PCDD/Fs in Ambient Air and Exposure Risk Assessment Around a Municipal Solid Waste Incinerator in Beijing].

Ambient air was sampled and analyzed around a municipal solid waste incinerator (MSWI) in Beijing from April 2014 to January 2015 to investigate the concentrations, profiles and seasonal variations of PCDD/Fs in the region using HRGC-HRMS technique. The mass concentrations and TEQ of 2,3,7,8-substituted PCDD/Fs in the air samples ranged from 8.9 to 140 pg·m and from 0.11 to 1.8 pg·m, respectively. The concentration values at 4 sampling sites in haze day in autumn and all 7 sampling sites in winter were higher than the ambient air standard of 0.6 pg·m for dioxins regulated in Japan. 1,2,3,4,6,7,8-HpCDF and OCDD dominated PCDD/Fs in all the samples for all four seasons with average contribution fractions of 20.5% and 14.0%, respectively, while 2,3,4,7,8-PeCDF was the dominant congener contributing to TEQ (43.3%). The spatial distribution basically exhibited a trend that the concentrations at all sites were comparable and not related to the distances from the source. Seasonal variation showed obviously higher concentration in winter than the other three seasons, which may attribute to the high concentration of ambient particulate matter due to domestic heating and worse atmospheric dispersion that occurred in winter. The homologue and congener profiles of PCDD/Fs in the air samples differed from those of the flue gas emission from the MSWI, consistent with the principle component analysis results. Dioxin inhalation exposure dose estimation showed that the dioxin inhalation exposure risk of residents living in the studied area was at a relatively safe level[0.060-0.224 pg·(kg·d)]. However, the dioxin inhalation exposure risk in heavily polluted seasons still needs great concerns.