Accumulation mechanisms and source-specific risks of PAHs across indoor and outdoor environments in a typical petrochemical industrial park.

Prolonged petrochemical activities severely exacerbate polycyclic aromatic hydrocarbon (PAH) contamination in surrounding areas; however, the differential accumulation mechanisms and source-specific risks of these pollutants across off-site indoor and outdoor environments remain poorly understood. This study systematically investigated PAH occurrence and risks in soil, road dust, and indoor dust surrounding a typical petrochemical industrial park to elucidate their divergent multimedia accumulation pathways. The mean concentrations of ∑16PAHs (μg/kg) in soil, road dust, and indoor dust within the study area were 5.94 × 102, 4.66 × 103, and 5.28 × 103, respectively, with a mixed combustion-related source identified as the largest contributor to regional PAH contamination. An integrated analysis combining gradient boosting decision trees (GBDT) and partial least squares structural equation modeling (PLS-SEM) indicated that multimedia PAH accumulation was shaped by the complex interplay between intrinsic matrix properties and external inputs. Specifically, total organic carbon (TOC) may directly influence PAH retention across the three matrices, while petrochemical sources and wind direction may indirectly affect PAH accumulation through matrix carbon content; traffic emissions likely intensify PAH loading in roadside environments. Additionally, source-specific assessments showed that road and indoor dust had higher PAH pollution and greater health risks than soil, with petrochemical-associated sources contributing most to both. This study advances understanding of PAH accumulation and distribution across multimedia environments under intensive industrial activities, providing a scientific basis for targeted PAH mitigation in industrial areas.