This paper illustrates the deficiency of the production approach as a tool to measure a country’s responsibility for international environmental impacts. A use approach is presented as a more suitable tool. The difference between the two approaches is determined by a better grasp of international trade, which can lead to environmental leakage when a country specialises in the production of environmentally friendly products and has the environmentally unfriendly products which it consumes produced abroad. We show that in the period 1995-2002 Belgium was on average a provider of air emission intensive products for the rest of the world. Environmental leakage was mostly negative. However, the evolution of the Belgian environmental terms of trade shows that by 2002 its imports had become considerably more air emission intensive with respect to its exports than in 1995. There are indications that this evolution is due to a considerable increase of extra-EU imports of air emission intensive products. This in turn could point to environmentally inspired offshoring. However, the currently available data do not allow us to test this hypothesis.