This session is focussed on the chemistry and physics of gases and particles over Boreal forest ecosystems. Measurements and modelling studies from recently performed summer intensive field campaigns (e.g. HUMPPA-COPEC 2010) will be presented here, although wintertime or seasonal studies are equally welcome. Studies of the environmental impact of natural Boreal forest emissions and anthropogenic sources (urban centers, biomass burning) would be presented in this session.