Sources, emissions, and fate of polybrominated diphenyl ethers and polychlorinated biphenyls indoors in Toronto, Canada.
ABSTRACT Indoor air concentrations of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) measured in 20 locations in Toronto ranged 0.008-16 ng·m(-3) (median 0.071 ng·m(-3)) and 0.8-130.5 ng·m(-3) (median 8.5 ng·m(-3)), respectively. PBDE and PCB air concentrations in homes tended to be lower than that in offices. Principal component analysis of congener profiles suggested that electrical equipment was the main source of PBDEs in locations with higher concentrations, whereas PUF furniture and carpets were likely sources to locations with lower concentrations. PCB profiles in indoor air were similar to Aroclors 1248, 1232, and 1242 and some exterior building sealant profiles. Individual PBDE and PCB congener concentrations in air were positively correlated with colocated dust concentrations, but total PBDE and total PCB concentrations in these two media were not correlated. Equilibrium partitioning between air and dust was further examined using log-transformed dust/air concentration ratios for which lower brominated PBDEs and all PCBs were correlated with K(OA). This was not the case for higher brominated BDEs for which the measured ratios fell below those based on K(OA) suggesting the air-dust partitioning process could be kinetically limited. Total emissions of PBDEs and PCBs to one intensively studied office were estimated at 87-550 ng·h(-1) and 280-5870 ng·h(-1), respectively, using the Multimedia Indoor Model of Zhang et al. Depending on the air exchange rate, up to 90% of total losses from the office could be to outdoors by means of ventilation. These results support the hypotheses that dominant sources of PBDEs differ according to location and that indoor concentrations and hence emissions contribute to outdoor concentrations due to higher indoor than outdoor concentrations along with estimates of losses via ventilation.
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ABSTRACT: The distributions of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Toronto, Canada and the surrounding suburban/rural area were examined. A series of temporally- and spatially-distributed air samples was collected over a 1-year period with a high-volume active air sampler at one downtown site and polyurethane foam passive air samplers at 19 sites. Passive sampler air concentrations of ΣPAHs ranged from 0.27 to 51 ng/m³. Concentrations of ΣPCBs ranged from 6.0 to 1300 pg/m³, and concentrations of ΣPBDEs ranged from 0.47 to 110 pg/m³. All compounds exhibited the highest concentrations in the urban core, and lowest concentrations in the surrounding rural areas, however the exact ratio depended on location since concentrations varied considerably within the city. Results from the application of a radial dilution model highlighted the influence of the central business district (CBD) of the city as a source of contaminants to the surrounding environment, however the radial dilution comparison also demonstrated that sources outside the CBD have a significant influence on regional contaminant concentrations. A strong relationship between temperature and partial pressure of the gas-phase PCBs, low molecular weight PBDEs and less-reactive PAHs suggested that their dominant emissions originated from temperature-controlled processes such as volatilization from local sources of PCBs, PAHs and PBDEs at warm temperatures, condensation and deposition of emissions at cold temperatures, and ventilation of indoor air with elevated concentrations. The relationship between temperature and atmospheric PAH concentrations varied along the urban-rural gradient, which suggested that in highly urbanized areas, such as downtown Toronto, temperature-related processes have a significant impact on air concentrations, whereas winter emissions from domestic heating have a greater influence in areas with less impervious surface coverage.Science of The Total Environment 05/2012; 429:272-80. · 3.26 Impact Factor