Long-Term Atmosphere Surveillance (2016–2021) of PM2.5-bound Polycyclic Aromatic Hydrocarbons and Health Risk Assessment in Yangtze River Delta, China

Long-term atmospheric quality monitoring of PM2.5 and PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) was performed in Wuxi from 2016 to 2021. A total of 504 atmospheric PM2.5 samples were collected, and PM2.5-bound 16 PAHs were detected. The PM2.5 and ∑PAHs level decreased annually from 2016–2021, from 64.3 to 34.0 μg/m3 and 5.27 to 4.22 ng/m3, respectively. The benzo[a]pyrene (BaP) of 42% of the monitoring days in 2017 exceeded the recommended health-based standard of the European Union (EU) at 1ng/m3. Five- and six-ring PAHs, including benz[a]anthracene (Baa), benzo[k] fluoranthene (Bkf), BaP, and benzo[g,h,i]perylene (Bghi), were the dominant components, indicating a prominent petroleum, biomass, and coal combustion contribution by molecular diagnostic ratios and positive matrix factorization analysis. Statistically significant temporal and spatial distribution differences of PM2.5, and ∑PAHs were also found. The toxicity equivalent concentration (TEQ) was 0.70 for total PAHs and the TEQ of BaP (0.178) was the highest, followed by Bkf (0.090), dibenz[a,h]anthracene (Dah) (0.048), and indeno[1,2,3-cd]pyrene (Ind) (0.034). The medians of the incremental lifetime cancer risk (ILCR) for long-term exposure to PAHs were 2.74E-8, 1.98E-8, and 1.71E-7 for children, teenagers, and adults, respectively, indicating that the carcinogenic risk of PAHs pollution in air was acceptable to local residents in this area. Sensitivity analysis showed that BaP, Bkf, and Dah significantly contributed to carcinogenic toxicity. This research supplies comprehensive statistics on the local air persistent organic pollutants profile, helps to identify the principle pollution source and compounds, and contributes to the prevention of regional air pollution.