Concentrations of twenty trace metals in ambient fine and coarse particles were characterized during the period of air quality deterioration of elevated particulate matters (PM episode) in winter in the suburban area, Yunlin County, Taiwan. The potential emission sources of fine-and coarse-size metals were identified using the enrichment factor (EF) analysis, principal component analysis (PCA) and backward trajectory model. The high concentrations of fine and coarse particles and their associated metals were observed during the PM episode in Yunlin County. Al, Fe, and Ca were predominant in fine and coarse particles for sampling periods, accounting for 75-85% of all selected elements. When the PM episode occurred, mean concentrations of fine-size Pb and As were increased to 132% and 116%, respectively, while average concentrations of coarse-size Fe, Al, Mn, Ti, and Co were increased to 1.1-2.2 times, in comparison with non-episode period. The mean value of fine-size As (6.67 ng m -3 ) obtained from the episode period exceeds the proposed European Union standard (6 ng m -3 ). EF values were decreased with increasing particle size for Sb, Se, As, Mo, Cr, Cu, V, Pb, Zn, Ni and Cd in both episode periods. Fine-size metals is likely to refer to coal combustion (36.5%), iron and steel industry (30.5%), vehicular emission and oil burning (16.3%), and Cu smelting source (13.1%), while coarse-size metals are associated with soil dust and crustal elements (61.6%), traffic-related re-suspended road dust (19.4%), industrial process (10.6%) and coal/oil combustion (6.3%) for the PM episode.
