A growth-decomposition (scale, technique and composition effect) covering 62 countries and seven manufacturing sectors over the 1990–2000 period shows that trade, through reallocations of activities across countries, has contributed to a 2–3% decrease in world SO2 emissions. However, when compared to a constructed counterfactual no-trade benchmark, depending on the base year, trade would have contributed to a 3–10% increase in emissions. Finally adding emissions coming from trade-related transport activities, global emissions are increased through trade by 16% in 1990 and 13% in 2000, the decline being largely attributable to a shift of dirty activities towards cleaner countries.