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Observations on PAH, PCB and PCDD/F trends in UK urban air, 1991-1995.

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<mark>Journal publication date</mark>07/1997
<mark>Journal</mark>Environmental Science and Technology
Issue number7
Number of pages5
Pages (from-to)2120-2124
Publication StatusPublished
<mark>Original language</mark>English


Ambient air concentrations at London and Manchester are reported for PCBs, PAHs, and PCDD/Fs from 1991 to 1995. This data set suggests that urban PAH concentrations are trending downward in the U.K. ∑PCB concentrations (∑ = congeners 28, 52, 101, 118, 138, 153, and 180) were usually 0.2−2 ng m-3 over the study period, with concentrations of the seven PCB congeners (∑PCB) in London generally 2−3 times higher than in Manchester. PCB concentrations have remained quite stable year-on-year over the study period. PCDD/F trends at the two sites were similar, with a decline through 1991−1994, followed by an upturn in 1995. Summer:winter seasonality of PCDD/Fs at both sites has been highly erratic year-on-year and compound-by-compound, far more so than for PAHs and PCBs. This is perhaps best interpreted as a sign that various sources (presumably combustion-derived) have contributed different mixtures of PCDD/Fs of different source strengths at different times to the air at these urban sites. Possible causes are discussed.