We assemble global spatially disaggregated panel data describing ambient particulate levels and transport, population, and economic and polluting activities. These data indicate the importance of country level determinants of pollution, of the equilibrium process that separates or brings together people and particulates, of urbanization, and of the composition of economic activity and energy production. We then develop an Integrated Assessment Model describing particulate emissions, economic activity and particulate dispersion. We quantify the model for 31 countries representing more than 60% of world population. Model results indicate the importance of general equilibrium adjustments to particulates policy. For example, uncompensated oil taxes and restrictions on agricultural burning may increase equilibrium pollution exposure by shifting labor to more polluting industries and locations. The model also indicates important cross-country heterogeneity in the effects of particulates policies. (joint with Lorenzo Aldeco and Matthew Turner)