the study of the large-scale influence of TSP on the environment needs a deep knowledge of particulate load and of chemical composition and distribution in the atmosphere (WHO 2000) . In the last decade concern on airborne particulates in urban areas led to a number of studies on the characterisation of TSP. Epidemiological studies pointed out a number of adverse health effects associated with atmospheric particles as they are vehicles of toxic substances (Dockery et al.1993;Schwartz et al.1996;Samet et al.2000) .As a consequence of the growing interest of the scientific community in chemical composition of particulates we started an extended study on TSP to obtain statistically significant data on its trace metal constituents.Indeed previous short-term studies carried out in this area (Shah et al.2004,2006;Shaheen et al.2005a,b) revealed elevated levels of some toxic trace metals over a particular duratin but so far no study has been reported on their annual and seasonal variations .These data stress the importance of a deeper knowledge of TSP composition,as well as their emission sources and of the role of atmospheric dispersion conditions in the area