The book describes the chemical analysis of airborne and roadside soil particles in the City of Kuala Lumpur, Malaysia. Its emphasis is on the identification and quantification of trace organic pollutants present in such environmental samples using gas chromatography-mass spectrometry (GCMS). The major compound groups analyzed include alkanes, polycyclic aromatic hydrocarbons (PAHs) and petroleum molecular markers. It is the spirit of this book to demonstrate the use of molecular markers as source identifiers by aiding in distinguishing biogenic versus petrogenic inputs to environmental samples. Comparing the organic pollutants content of the different environmental compartments (i.e., airborne particles and roadside soil particles) is as well illustrated to help understand the transport and fate of these pollutants in the environment. Typical fragmentograms of the characterized organic compounds are presented throughout the text.