Long-Term Variability, Source Apportionment and Meteorological Controls of PM_2.5-Bound Polycyclic Aromatic Hydrocarbons at a Southern Italian Mediterranean Urban Site

A three-year (January 2020–December 2022) daily dataset of 16 polycyclic aromatic hydrocarbons (PAHs) co-sampled with PM2.5 and a suite of meteorological variables at a Mediterranean coastal urban site in southern Italy (Pomigliano d’Arco, Campania) is presented and analysed. Raw PAH time series were decomposed into a long-term trend component (LT), a seasonal component (ST), and a residual component (RT) using an iterative missing-value-robust Kolmogorov–Zurbenko (KZ) moving-average filter. Spearman rank correlations between PAH concentrations and four meteorological predictors (mean temperature, relative humidity, mean wind speed, and maximum wind speed) were computed for each congener. Diagnostic molecular ratios — Fluoranthene/(Fluoranthene+Pyrene), BaP/BghiP, Indeno[1,2,3-cd]pyrene/(IcdP+BghiP), and Benz[a]anthracene/(BaA+Chrysene) — were evaluated seasonally and subjected to an information-theoretic Bayesian mixture modelling procedure (SNOB/MML) to estimate the number and nature of prevailing emission source classes. Total PAH concentrations (sum of 16 congeners) ranged from <1 ng m−3 in summer to 46 ng m−3 during winter high-pollution episodes, with BaP peaking at ≈6.7 ng m−3. Pronounced seasonal variability was driven primarily by residential heating emissions, and the incremental lifetime cancer risk (ILCR) for inhalation exposure reached 1.03×10−4 (95% CI: 0.88−1.20×10−4) during the heating season, exceeding standard regulatory thresholds. An anomalous near-background PAH signal during spring 2020 is attributed to the COVID-19 national lockdown, which reduced total PAH concentrations by approximately 85% relative to the seasonal component predicted by the iterative moving-average filter for the same calendar window. Source apportionment via diagnostic ratios identifies residential/biomass combustion as the dominant cold-season source and vehicular emissions as the prevailing warm-season source. These results provide a novel characterisation of PAH pollution dynamics in the undersampled southern Mediterranean and offer insights for targeted abatement policies.