The concentrations of total suspended particulate (TSP), fine particles PM2.5 (with aerodynamic diameter < 2.5 mu m), coarse particles PM2.5-10 (with aerodynamic diameter 2.5-10 mu m), and water-soluble inorganic ions were studied at two offshore sampling sites, Taichung Harbor (TH) and Wuci Traffic (WT), near Taiwan Strait in central Taiwan during March 2004 to January 2005. Statistical analyses were also carried out to estimate the possible sources of particulate pollution. Experimental results showed that the average mass concentrations of TSP, PM2.5 and PM2.5-10 at TH and WT sampling sites were 154.54 +/-31.45 and 113.59 +/- 31.94 mu g m(-3), 54.03 +/- 16.92 and 42.76 +/-12.52 mu g m(-3), and 30.31 +/- 9.79 and 24.16 +/- 7.27 mu g m(-3), respectively. The dominant inorganic ions at two sampling sites were SO42-, NO3-, and NH4+ for TSP and PM2.5, but that were Ca2+ Cl-, and Na+ for PM2.5-10. The concentrations of most particulates and inorganic ions were higher in winter at both two sampling sites, and were higher at TH than WT sampling site in each season. From statistical analysis, air-slake of crust surface, sea-salt aerosols, agriculture activities, coal combustion, and mobile vehicles were the possible emission sources of particulate pollution at TH and WT sampling sites. (c) 2005 Elsevier B.V. All rights reserved.