A global chemistry climate model is used in conjunction with a regional chemistry-transport model dedicated to air quality studies to investigate the impact of anthropogenic emission changes, under several scenarios, on western European summertime surface O3 levels in 2030. The implementation of presently decided emission control legislation in the individual countries worldwide leads to a geographically heterogeneous impact on summertime surface O3 levels over Europe. A decrease of the averaged O3 mixing ratio reaching -3 ppbv is predicted in southern areas whereas an increase reaching up 4 ppbv is calculated in northwestern Europe. The benefit of European emission control measures is found to be significantly counterbalanced by increasing global O3 levels and subsequent long range transport since both are of the same magnitude (up to 4 ppbv) but opposite in sign. However, the net effect of both global and European emission changes is a significant decrease of O3 extreme episodes during summertime.