Does income inequality exacerbate haze pollution? a cross-country analysis (2000–2020)

Income inequality and air pollution constitute two deeply connected obstacles to sustainable development. Using a panel of 217 countries spanning 2000–2020, this study empirically investigates how income inequality is related to haze pollution. Employing multiple measures of income inequality, we find robust evidence that higher inequality significantly exacerbates haze pollution. More precisely, when the Gini coefficient rises by one standard deviation, average annual exposure to fine particulate matter (PM2.5) increases by 0.669%, ceteris paribus. Quantile regression results further reveal substantial heterogeneity across the pollution distribution: reductions in income inequality yield larger improvements in air quality in countries experiencing more severe haze pollution. Additional analysis highlights the role of poverty as an important channel, showing that lower poverty levels are associated with reduced haze pollution. A series of heterogeneity analyses and robustness tests confirm that these results remain stable across alternative specifications and subsamples. Overall, the results suggest that income redistribution policies can generate complementary social and environmental benefits. By reducing income inequality and alleviating poverty, governments may simultaneously improve air quality and advance sustainable economic development, offering a viable pathway toward achieving both social equity and environmental protection.