Distribution, sources, and health risk assessment of polycyclic aromatic hydrocarbons (PAHs) in dust from petrol stations in the main urban districts of Guiyang.

As typical urban service facilities, petrol stations are vulnerable to pollution caused by motor vehicle exhaust and petrol spills. Dust samples collected from petrol stations in the main urban districts of Guiyang were analyzed in this study to determine the concentrations, sources, and health risks of 16 polycyclic aromatic hydrocarbons (PAHs). All 16 PAHs were detected in over 90% of the dust samples, with total concentrations (∑16PAHs) ranging from 0.190 to 14.968 mg/kg (mean: 1.550 mg/kg), a mean level considered moderate when compared to other cities in China and globally. The predominant PAHs in the dust were medium molecular weight (MMW) and high molecular weight (HMW) compounds, which together accounted for 80.6% of the mean concentration of the ∑16PAHs. The frequent occurrence of traffic congestion was the primary factor contributing to the higher mean concentrations of MMW PAHs, HMW PAHs, carcinogenic PAHs (∑carPAHs) and ∑16PAHs in dust from Nanming districts (NMD) and Yunyan districts (YYD). Diagnostic ratio results revealed that the PAHs were predominantly derived from vehicle exhaust, with a lesser contribution from fuel spillage and biomass combustion. The results of the incremental lifetime cancer risk (ILCR) showed that ingestion, dermal contact, and inhalation posed no carcinogenic risk to non-occupationally exposed adults (NOEA). For petrol station workers (PSW), dermal contact presented a high carcinogenic risk, while the ingestion pathway posed a potential carcinogenic risk. Personal protective measures, such as wearing protective suits and gloves, should be implemented to reduce the ILCR from dermal contact, while the use of masks and increasing frequency of personal cleaning could reduce the ILCR from ingestion. Furthermore, promoting the adoption of green energy sources, such as electric vehicles, can effectively reduce fuel consumption and shorten exposure time at petrol stations, thereby lowering the concentration of pollution sources.