This study aims to determine the concentrations of the trace metals (TM) and water soluble inorganic ions (WSII) of the PM2.5 pollutant collected in the suburban industrial-residential airshed during the southwest (SW), inter-monsoon (IM) and northeast (NE) monsoons in Skudai, Johor Bahru. The PM2.5 samples were collected using the MiniVol™ portable air sampler equipped with filter paper. The TM and WSII of PM2.5 were determined by using the inductively coupled plasma-mass spectrometry (ICP-MS) and ion chromatography (IC), respectively. The sources of the PM2.5 composition were determined us...