“…The concentrations of OPEs in the particles of Chengdu were comparable to those reported for Beijing (0.257-8.36 ng m −3 ) (D. , 6 OPEs for a Shanghai urban site (6.6 ng m −3 ) (Ren et al, 2016) and 6 OPEs for Bursa (6.5 ng m −3 ) but higher than those in Houston, United States ( 12 OPEs, 0.16-2.4 ng m −3 ) (Clark et al, 2017), Dalian ( 9 OPEs, 0.32-3.46 ng m −3 , 1.21 ± 0.67 ng m −3 ) (Y. , the European Arctic (0.033-1.45 ng m −3 ) (Salamova et al, 2014b), the North Pacific and Indian oceans (0.23-2.9 ng m −3 ) (Möller et al, 2012), the Yellow Sea and Bohai Sea (0.044-0.52 ng m −3 ) (Li et al, 2018), the South China Sea (0.047-0.161 ng m −3 ) (Lai et al, 2015) and the North Atlantic and Arctic oceans (0.035-0.343 ng m −3 ) . The detected OPE concentrations were also lower than those in Guangzhou and Taiyuan ( 11 OPEs, 3.10-544 ng m −3 ) (Chen et al, 2020), H. Yin et al: Seasonality, distribution and sources of OPEs in PM 2.5 in Southwest China Bursa, Turkey ( 6 OPEs, 0.53-19.14 ng m −3 ) (Kurtkarakus et al, 2018) and 20 industrial sites in an urban region in Guangzhou, China ( 12 OPEs, 0.52-62.75 ng m −3 ) (Wang et al, 2018).…”