Transboundary transport of firework emissions from China enhances PM2.5 and oxidative potential in Korea during the Lunar New Year

This study demonstrates that long-range transport (LRT) is a major driver of episodic PM 2.5 pollution in Korea. A distinct transboundary event, Firework–LRT (February 10–15, 2024), during the Lunar New Year in China, markedly elevated PM 2.5 mass and oxidative potential (OP). Positive matrix factorization (PMF) analysis indicated that firework-related aerosols contributed 16.6 ± 7.0 μg m −3 (38%), peaking at ~60%, and were enriched in K, Mg, Ba, and Cu, consistent with pyrotechnic signatures. Satellite aerosol optical depth (AOD), nationwide observations, and trajectory analyses consistently confirmed long-range transport from eastern China with subsequent eastward propagation to Japan. Firework–LRT was associated with enhanced OP, reflecting increased aerosol toxicity. The observed relationships between OP, transition metals, and secondary inorganic aerosols (SIA) suggest that redox-active species and atmospheric aging jointly amplify oxidative activity. These findings demonstrate that episodic transboundary emissions can substantially elevate both PM 2.5 mass and toxicity, underscoring the need for coordinated regional air quality management in Northeast Asia.