Spatial and seasonal distributions of parent, nitrated, and oxygenated PAHs and health risks in a major industrial city in Korea

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous atmospheric pollutants, and their nitrated (NPAHs) and oxygenated (OPAHs) derivatives originate from both primary sources and secondary atmospheric reactions. This study investigated the seasonal and spatial distributions, emission sources, and potential health risks of PAHs, NPAHs, and OPAHs using polyurethane foam-based passive air samplers (PUF-PASs) across 20 sites in Ulsan, South Korea. The concentrations of Sigma 21 PAHs were highest in fall and winter. In contrast, the Sigma 17 NPAH and Sigma 9 OPAH levels showed limited seasonal variation, likely reflecting enhanced photochemical formation in warm seasons and greater primary emissions in cold seasons. Industrial sites exhibited consistently higher levels, reflecting the influence of local emission sources. Correlation analysis and diagnostic ratios indicated that NPAHs and OPAHs were influenced by both primary sources and secondary formation, with a stronger influence of primary emissions on OPAHs in winter. The cancer risk remained below the US EPA threshold (1.0E-06) at all sites. However, relatively higher values were observed in some urban areas. Non-priority PAHs contributed considerably to the total BaPeq, indicating the need for further toxicological evaluation. This study provides a comprehensive understanding of the emission characteristics and secondary formation of PAHs and their derivatives in an industrial city in South Korea.