Fig. 4: Mechanism on governance experiences.

a–c, The effects of exchanged city leaders with and without working experiences in environment-related departments on firm-level COD (a), ammonia nitrogen (b) and wastewater (c) (Supplementary Note 10 and Supplementary Table 31). By environment-related departments, we refer to departments of environmental protection and regulation, natural resources and water resources at various levels. The P values for the coefficients of ‘with experiences in environment-related departments’ and ‘without experiences’ are all 0.000. d–f, The effects of two types of intercity personnel exchanges on firm-level COD (d), ammonia nitrogen (e) and wastewater (f). We ranked all cities according to their water pollution reduction rates. The top 33% cities with the highest levels of water pollution reduction rate are defined as first-mover cities since they have the best performance in pollution control and environmental governance, while the bottom 33% cities are defined as late-comer ones. We then decomposed intercity exchange of city leaders (exchange) into two types: ‘exchanges from first-movers to late-comers’ and ‘other exchanges’, and include both in equation (1), while controlling for a city’s initial pollution intensity (Supplementary Note 10 and Supplementary Table 33). For the COD and ammonia nitrogen regressions, the P values for the two coefficients are all 0.000. For wastewater regression, the exact P values are 0.047 and 0.000, respectively. The data are presented as the estimated coefficients (hollow circles) ±95% confidence intervals (error bars).