Identification of chemical tracers in the characterisation and source apportionment of inhalable inorganic airborne particles: an overview

The acquisition of increasingly large analytical datasets from standardized air pollution monitoring stations allows more effective characterization of the fine aerosol cocktail breathed daily by modern urban populations. It is increasingly clear from such data that there is great variability in the chemical composition of inorganic inhalable particulate matter (PM(10) = < 10 mu m in size) in both space and time. Such variability can be demonstrated using selected tracer elements which, combined with source apportionment techniques, allow differentiation between natural (geological) and anthropogenic sources such as traffic and various industries. These tracer elements, which are commonly toxic metals, can be shown to concentrate in the finer, more deeply inhalable PM fraction, and are thus linked to potential inflammation and oxidative stress after inhalation. Legislation concerned only with measuring physical PM mass concentrations therefore fails to address potential health effects linked to chemical variations in ambient aerosols.