Polycyclic Aromatic Hydrocarbons (PAHs) and their oxygenated derivatives (OPAHs), collectively termed Polycyclic Aromatic Compounds (PACs), are hazardous air pollutants with documented carcinogenicity. Benzo[a]pyrene (B[a]P), a representative PAH, has an established European annual target concentration of 1 ng m⁻³ due to its toxicity. These compounds primarily originate from incomplete combustion processes, including biomass and fossil fuel burning, and undergo further atmospheric transformation. Systematic monitoring of PACs in urban settings is essential for understanding their sources and evaluating public exposure risks. A total of 160 24-hour aerosol samples were collected on quartz filters over a three-year period (2022–2024) in Heraklion, Crete—a Mediterranean city with a significant seasonal population increase due to tourism. Samples were analyzed for PACs, Organic and Elemental Carbon (OC/EC), ions, metals, and traffic-related organic markers using the methods of Tsiodra et. al., 2025 and Paraskevopoulou et. al., 2019. Source attribution and carcinogenic risk assessments were conducted using chemical speciation data and toxic equivalent factors (BaPeq). PAC concentrations exhibited strong seasonal variation, with winter levels significantly exceeding summer values. Total PAHs were nine times higher in winter, and OPAHs and B[a]P showed 18-fold increases, largely due to residential biomass burning. Summer samples indicated a greater presence of low molecular weight PAHs (e.g., phenanthrene), suggesting a dominant influence from traffic and marine emissions. Carcinogenic risk, as measured by BaPeq, was markedly elevated in winter (17.9 ng m⁻³) compared to summer (0.5 ng m⁻³). This study provides the first long-term dataset on PAC exposure in this region of Greece and highlights the seasonal impact of combustion sources on urban air quality and health risk.