This study concentrates on fine particulate matter emissions from the residential wood combustion sector in Denmark, Finland, Norway and Sweden. The focus on this sector is due to its importance when it comes to PM emissions in the Nordic countries compared to the rest of Europe. Further, the lack of regulations and the possible potential to decrease the PM emissions in this sector have been other driving forces.The purpose with the project has been twofold:* to compare and harmonise the data regarding PM2.5 emissions and cost-efficient measures in the residential wood combustion sector in the Nordic countries, and* to create a well working Nordic network for particulate matter emissions.