Atmospheric polycyclic aromatic hydrocarbon concentrations in a semi-urban site: temporal variation, risk assessment, source identification, and estimation of levels in diverse environments.

This study investigates atmospheric polycyclic aromatic hydrocarbons (PAHs) in the semi-urban area of Görükle, Bursa, Turkey, from June 2021 to February 2022, reporting an average ∑16 PAH concentration of 24.85 ± 19.16 ng/m³. Seasonal variations showed winter levels approximately five times higher than summer, attributed mainly to residential heating emissions and meteorological influences such as temperature and mixing height. The dominant PAHs were 2- and 3-ring compounds, primarily present in the gas phase, while heavier PAHs accumulated more in soil and plant media as estimated by equilibrium partitioning models. Source apportionment using diagnostic ratios, principal component analysis, and air mass trajectory modeling identified vehicle emissions and combustion for heating as primary pollution sources, with some influence from industrial areas like Kocaeli. Cancer risk assessment based on benzo(a)pyrene equivalents indicated low lifetime cancer risks for both adults and children in the region.