In most low- and middle-income countries pollution levels are higher in wealthier areas

Air pollution is a major threat to health, and the dangers are particularly acute in low- and middle-income countries. However, little is known about how the burden of pollution is spread across the wealth distribution in these countries. This paper uses new data providing high-resolution wealth estimates for more than 100 low- and middle-income countries, combined with equally high-resolution estimates of air pollution, to estimate how wealth is correlated with ambient air pollution around the world. The findings show that on average air pollution is positively correlated with wealth, but the relationship is highly heterogeneous across countries. The fact that air pollution and wealth are both disproportionately high in urban areas, where economic activity is largely concentrated, appears to drive this relationship. When the analysis is limited to anthropogenic sources of pollution, the relationship becomes less heterogeneous and more systematically positive. The paper also examines the relationship between pollution exposure and wealth within large cities around the world. Again, the findings show substantial heterogeneity across cities. The paper explores several hypotheses for this heterogeneity but does not find a single explanation. Economic concentration within cities appears to explain some of the relationship. Cities with more concentrated economic opportunity tend to have more positive correlations between pollution and wealth.