Journal Clean WAS (JCleanWAS)

Polycyclic aromatic hydrocarbons (PAHs) are harmful combustion byproducts with carcinogenic and mutagenic properties, and their carcinogenic potential persists in indoor environments. Vulnerable populations, particularly children, are at heightened risk of exposure. This study quantified schoolchildren’s exposure to fine particulate matter-bound PAHs (PM2.5-bound PAHs) in five urban classrooms between April 2024 and March 2025 using gas chromatography-mass spectrometry (GC-MS). Total PAH concentrations ranged from 1,140 to 1,470 ng/m³, with total toxic equivalent quotient (TEQ) values of 0.172-0.251 ng/m³, primarily driven by benzo[a]pyrene (B[a]P) and dibenzo[a,h]anthracene (DahA), which accounted for 62-68% of ETEQ. Pediatric incremental lifetime cancer risk (ILCR) estimates (2.47 – 3.6 * 10 ^ – 7) indicated low risk (<10 threshold) but were 1.75 times higher than adult estimates Regression models effectively predicted ∑TEQ (R ^ 2 = 0.958) and ILCR (R ^ 2 = 0.982) with 5-fold cross-validation confirming robustness (R²_cv = 0.92-0.94). K-means clustering \ k = 2 ; Silhouette score = 0.479) revealed compounddominated -exposure patterns. These findings highlight the need for targeted policy interventions, including improved ventilation and emission controls, to protect children’s health in indoor environments.