Fig. 2: The effect of intercity exchange of city leaders on firm-level water pollution.

a, The impacts of personnel exchange on firm-level COD, ammonia nitrogen and wastewater. The data are presented as the estimated coefficients (dots) ±95% confidence intervals (error bars). The P values for the coefficients of personnel exchange are all 0.000. The sample sizes are 566,765 (COD), 382,730 (ammonia nitrogen) and 583,250 (wastewater). b–d, The contribution of intercity exchange of city leaders to water pollution reduction compared with the national total water pollution reduction during 2006–2013 for COD (b), ammonia nitrogen (c) and wastewater (d). The solid red lines represent the overall change in national industrial water pollution (including the effects of personnel exchanges), and dashed red lines represent the counterfactuals (without the effects of personnel exchanges). The negative values denote water pollution reduction, while positive values represent increases in water pollution. The red shades display the water pollution reduction induced by intercity exchange of city leaders during 2006–2013, which is calculated based on the estimated overall effects in baseline regressions (Supplementary Table 3). The overall change in national industrial water pollution is calculated using data from the Ministry of Ecology and Environment of China (Supplementary Note 6).