Ambient air polycyclic aromatic hydrocarbon (PAH) samples were collected at traffic, residential, coastal, and semiurban sites in Bursa, Turkey, between June 2008 and June 2009. For the traffic, residential, coastal, and semiurban sites, the average gas phase total PAH (a(12)PAH) concentrations were 113 +/- A 131, 142 +/- A 204, 53 +/- A 73, and 19 +/- A 34 ng/m(3), respectively, whereas the average particle phase total PAH concentrations were 28 +/- A 36, 56 +/- A 85, 24 +/- A 40, and 11 +/- A 23 ng/m(3), respectively. Phenanthrene and fluoranthene had the highest concentrations of all of the sampling sites in the gas phase. The PAH concentrations in the heating period were 5-7 times greater than the nonheating period concentrations. Principal component analysis (PCA) was used to investigate the relationship between the levels of PAHs determined in ambient samples and their possible sources. The PCA model shows that coal combustion and vehicle emissions affected PAH emissions. Moreover, the molecular diagnostic ratios indicated that coal-burning and traffic emissions were the dominant PAH sources. The multiple linear regression analysis indicated that the meteorological parameters also affected the ambient PAH concentrations. The sampling site characteristics, meteorological conditions, dispersion, and local sources all affected the concentration levels.