The MATCH (Mesoscale Atmospheric Transport and CHemistry) model has been developed as a tool for air pollution assessment studies on different geographical scales. The MATCH system is based on an Eulerian atmospheric transport model, including physical and chemical processes governing sources, atmospheric transport and sinks of oxidised sulphur and oxidised and reduced nitrogen. With the MATCH system, air pollution contributions from different source types like traffic, industry, shipping, farming etc. can be obtained. Using a combination of air and precipitation chemistry measurements and the MATCH dispersion model, the contribution of air pollution and deposition from long-range transport can be quantified in the model region. The calculations for the year 1994 show that the Swedish import was 5.5 times larger than the export for sulphur and 4.4 times larger for reduced nitrogen, while the Swedish import of oxidised nitrogen only exceeded the export by 10%.