Spatiotemporal characterization of VOC hotspots in small-scale industrial complexes in Yangsan, Korea, using real-time mobile SIFT-MS.

This study investigated the emission characteristics and high-concentration hotspots of volatile organic compounds (VOCs) in four industrial complexes in Yangsan, Korea-Sanmak, Soju, Eogok, and the Yangsan General Industrial Complex-using real-time mobile selected ion flow tube mass spectrometry (SIFT-MS). Mobile monitoring was conducted repeatedly during winter (November-March, 2021-2024) under daytime conditions (10:00-14:00). A GPS (Global Positioning System)-based grid system enabled GIS (Geographic Information System)-based spatial analysis to determine VOC distributions and hotspot locations. Target compounds included VOCs measurable by SIFT-MS that are classified as hazardous air pollutants under the Clean Air Conservation Act. Statistical indices such as arithmetic mean, geometric mean, maximum, and percentile values were used to compare VOC patterns by complex and compound group. Oxygenated VOCs (OVOCs; methanol, formaldehyde) dominated background concentrations in Sanmak, Soju, and Eogok, whereas aromatic VOCs (toluene, xylenes) prevailed in the Yangsan General Complex. Hotspot analysis identified butanone and methanol in Sanmak; methanol, toluene, and chloroform and dichloromethane (DCM) in Soju; methanol, xylenes, and butanone in Eogok; and toluene, xylenes, and methanol in the Yangsan General Complex. These spatial and compositional trends corresponded with PRTR (Pollutant Release and Transfer Register) emission data and industrial sector distributions. The findings demonstrate distinct VOC emission behaviors across small- and medium-scale complexes, driven by process type, solvent use, and ventilation. This study provides a scientific basis for developing site-specific, event-responsive VOC management strategies.