The SAPPHIRE project will deliver the most detailed information to date on the chemical composition and sources of airborne particulate matter in rural and urban residential areas of Ireland. This information will provide policy makers with a sound scientific basis for development of strategies to reduce particulate pollution, particularly in relation to the use of solid fuels for home heating. The research will involve field measurements of a range of air pollutants in specially selected locations in Ireland. Efforts will be focussed on determining the chemical composition of airborne particulate matter using both on-line (aerosol mass spectrometry) and off-line analytical methods (ion chromatography, GC-MS and ICP-OES). Source apportionment modelling will also be performed to attribute the particles to specific sources. The objectives of the project are to determine the chemical composition of fine particulate matter (PM2.5) present in locations representative of urban and rural residential areas in Ireland. Also, to conduct a source apportionment study of PM2.5 in the urban and rural areas and quantify the contributions of major sources including road traffic and domestic solid fuel burning. The measurement and analytical methods employed in the project will enable separation of the individual contributions from combustion of coal, peat and wood/biomass in residential areas. Finally, conclusions will be drawn about the chemical speciation and sources of PM2.5 in rural and urban residential areas in Ireland and provide policy makers with relevant scientific information to support development of effective strategies for reducing particulate pollution.