Objective To investigate the pollution levels of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 in an urban area of Ningbo, identify their sources, and evaluate their potential health risks.
Methods Particulate matter samples were collected from the four-storey roof platform of Ningbo Jiangbei Children's Hospital from 10th to 17th of every month except September (from 8th to 15th) in 2016. High performance liquid chromatography was used to determine the levels of 16 polycyclic aromatic hydrocarbons (PAHs) in collected atmospheric PM2.5 samples. PAHs ratios were used to identify sources of PAHs. The inhalation model recommended by Risk Assessment Guideline for Superfund of the US Environmental Protection Agency was used to assess the health risks of PAHs.
Results The average annual concentration of PM2.5 was 54 μg/m3, exceeding the national limit (35 μg/m3). The total concentrations of 16 PAHs in PM2.5 were between 1.60 and 31.26 ng/m3, and the average value was 6.11 ng/m3. The average annual concentration of BaP in PM2.5 was 0.50 ng/m3, which did not exceed the ambient air quality standard of China (1 ng/m3), but the unqualified rate of daily average concentration was 2.1%. The total concentrations of 16 PAHs were high in winter and low in summer. According to the predetermined diagnostic ratios, the PAHs in PM2.5 at the selected sampling site were mainly derived from gasoline combustion. There was no carcinogenic risk (Risk=0.54×10-6) but was non-carcinogenic risk (HQ=1.06) if populations were exposed to the sampled PAHs in PM2.5.
Conclusion PM2.5 pollution is identified at the sampling site. Exposure to PAHs in PM2.5 by inhaling in the selected area poses no human carcinogenic risk but has human non-carcinogenic risk.
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