Source apportionment of airborne particulate matter has assumed increasing importance in recent years, driven by two underlying causes.  Firstly, legislative pressure to reduce airborne concentrations of particulate matter has highlighted the need for reliable quantitative knowledge of the source apportionment of particulate matter in order to devise cost-effective abatement strategies.  The use of source inventories alone is inadequate as these are limited in the components which they are able to quantify reliably and take no account of the different ground-level impacts of pollutants released at different altitudes within the atmosphere.  Consequently, there has been a need for the application of methods capable of source apportionment of ground level concentrations.  Secondly, there has been a growing recognition that abatement of PM mass, taking no account of source, chemical composition or particle size, may not be a cost-effective approach if particulate matter differs according to its source of emissions or physico-chemical characteristics.  Furthermore, from this, a number of recent epidemiological studies have attempted to combine receptor modelling results with time series studies of health effects (e.g. Thurston et al., 2005;  Mostofsky et al., 2012; Ostro et al., 2011).