The chemical mass balance model was applied to atmospheric Polycyclic Aromatic Hydrocarbons (PAHs) in Istanbul, Turkey. A total of 326 airborne samples were collected and analyzed for 16 PAHs and Total Suspended Particles (TSP) in the September 2006 December 2007 period at three monitoring stations: Yildiz, DMO (urban sites) and Kilyos (rural site). The total average PAH concentrations were 100.66 +/- 61.26, 84.63 +/- 46.66 and 25.12 +/- 13.34 ng m(-3) and the TSP concentrations were 101.16 +/- 53.22, 152.31 +/- 99.12, 49.84 +/- 18.58 mu g m(-3) for Yildiz. DMO and Kilyos stations respectively. At all the sites, the lighter compounds were the most abundant, notably Nap, AcPy and PA. The average correlation values between TSP and total heavier PAH were greater than 0.5 for Yildiz and DMO stations. The patterns of PAH and TSP concentrations showed spatial and temporal variations. PAH concentrations were evaluated for the PAH contribution from four sources (diesel engines, gasoline engines, natural gas combustion, and coal + wood burning). Vehicle emissions appear to be the major source with contributions of 61.2%, 63.3% and 54.1% for Yildiz. DMO and Kilyos stations respectively. Seasonal and yearly variations had different trends for all sites. (C) 2010 Elsevier B.V. All rights reserved.