Unveiling distribution and health risks of polycyclic aromatic hydrocarbons (PAHs) bound to PM2.5 in indoor and outdoor environments of urban primary schools

Abstract

Polycyclic aromatic hydrocarbons (PAHs) exposure in children has been associated with various health impacts, including increased risk of asthma, skin diseases and allergies. In this study, we investigated the distribution, possible sources, and potential health risks of PAHs bound to fine particulate matter (PM2.5) collected in urban primary school environments. PM2.5 samples were collected using two identical low-volume samplers (LVS) equipped with quartz fibre filters (QMA) in both indoor and outdoor environments. The samples underwent ultrasonic extraction with a mixture of dichloromethane/n-Hexane (1:1) before analysis using gas chromatography-mass spectrometry (GC-MS). The results showed the mean total concentration of PAHs (∑PAHs) for indoor and outdoor environments were 4.34 ± 2.39 ng m− 3 and 5.62 ± 2.39 ng m− 3, respectively. High molecular weight (HMW) PAHs with five- and six-rings accounted for over 60% of outdoor and indoor ∑PAHs. Diagnostic ratio and source identification by principal component analysis revealed that traffic-related emissions from both gasoline and diesel-powered engines, as the primary contributors to ∑PAHs in school environments. The results of the total carcinogenic risk for children aged 7–12 years in all schools caused by the presence of PAHs compounds in outdoor environments was acceptable. In some indoor environments, the values at certain schools exceeded the standard threshold of 10− 6-10− 4, indicating potential health risks. Given that PAHs are primarily generated from transportation activities, it is necessary to monitor and control the sources of their emissions, particularly in schools that are significantly impacted by these pollutants.