Pollution characteristics of PM2.5 and PM1.0 at urban and background sites in South Korea: Focusing on health risks of PAHs and heavy metals

Abstract

Although smaller particles are considered more harmful to human health, the need for independent management of PM1.0 remains debated. In this study, PM2.5 and PM1.0 samples were collected for 15-20 days per season during 2020-2021 at an urban site in Seoul (SE) and a background site on Baengnyeong Island (BN), South Korea, to monitor PAHs and metals. Both sites showed higher Sigma 13 PAH concentrations in winter (SE: 12.6 for PM2.5 and 9.59 for PM1.0; BN: 9.37 and 5.58 ng/m3), while Sigma 10 metal concentrations increased in winter (SE: 769 and 373; BN: 660 and 340 ng/m3) and fall (SE: 503 and 248, BN: 403 and 223 ng/m3). Backward trajectory analysis identified northeastern and northern China and North Korea as major source regions. BN frequently experienced CHMs episodes associated with air masses transported from North Korea. SHAP results revealed that seasonal variables were primary drivers of CPAHs, whereas particle size was the dominant factor influencing CHMs. Cancer risk associated with PAHs was higher at SE (6.7 & times; 10-8 and 4.7 & times; 10-8), whereas that from heavy metals was higher at BN (1.0 & times; 10-5 and 5.6 & times; 10-6). Risk normalized by PM mass was significantly higher for PM2.5, indicating a more efficient enrichment of PAHs and heavy metals in the PM1.0-2.5 fraction. PAH sources were similar across sites and particle sizes, while metal sources varied with particle size and meteorological condi-tions. Overall, enhancing the current PM2.5-based management framework by incorporating PM1.0 characteristics is recommended to better protect human health risks.