This report presents the EMEP activities in 2016 and 2017 in relation to transboundary fluxes of particulate matter, photo-oxidants, acidifying and eutrophying components, with focus on results for 2015. It presents major results of the activities related to emission inventories, observations and modelling. The report also introduces specific relevant research activities addressing EMEP key challenges, as well as technical developments of the observation and modelling capacities. An important topic this year is the transition to the new EMEP grid and resolution. For the first time, officially reported fine scale emissions (0.1◦×0.1◦ resolution) have been used in the EMEP MSC-W model runs for air pollution assessment. The impacts of this change on model results and its comparisons to observations are analyzed in this report.