Production-based PM2.5 emissions linked to foreign consumption. (a) The largest interregional flow of emissions embodied in trade (Gg per year) from dominant net exporting countries (blue) to the dominant importing countries (red). Flows to and from Western Europe are aggregated and include the United Kingdom, Germany, France, Switzerland, Italy, Spain, Sweden, Luxembourg and the Netherlands; (b) the interregional flow pattern of PM2.5 emissions embodied in the global trade system (Gg per year) among 20 aggregated regions. The flow from each region represents PM2.5 emissions embodied in exported commodities to the other end of the link, and the link colour corresponds to the regions with greater exports. (Online version in colour.)