Episodic and source-resolved VOC emissions in a petrochemical complex: Insights from real-time measurements.

Volatile organic compound (VOC) emissions from petrochemical complexes are highly variable and difficult to quantify using conventional monitoring. We conducted a month-long, on-site measurement campaign within the Daesan Petrochemical Complex in South Korea using PTR-ToF-MS, enabling real-time characterization of 85 VOC species with minimal atmospheric dilution. VOC concentrations were dominated by episodic, process-driven releases rather than diurnal or meteorological patterns. Oxygenated VOCs accounted for 81% of total mass, with extreme methanol and acetone levels reflecting process-specific emissions. Positive Matrix Factorization resolved seven major industrial sources, including catalyst production, plastics manufacturing, chlorinated chemical production, high-temperature pyrolysis, and refinery operations. Combining PMF with CPF and reactivity metrics showed that catalytic and pyrolysis-related sources contributed disproportionately to ozone formation, while TPA production dominated SOA formation potential. These results demonstrate that short-term industrial emission spikes strongly influence local atmospheric reactivity, underscoring the need for near-source, high-resolution monitoring. The findings provide a framework for identifying uncontrolled emissions and support targeted mitigation strategies within industrial complexes.