A comment on "Informed Enforcement: Lessons from Pollution Monitoring in China" by Sebastian Axbard and Zichen Deng

Axbard and Deng (2024) exploit the rollout of new pollution monitors in China in 2015 in 177 medium-size cities to study the effect of air-quality monitors on enforcement actions by local governments and air quality. In their main difference-in-difference analysis, they identify the change in the probability of enforcement for firms that are close to versus further away from the monitor. They find that being within 10km of a monitor increases the probability that a firm receives any enforcement action by 0.0033 (standard error 0.00056) relative to a mean of 0.0046. Computationally, we successfully reproduce the main claims of the paper. We observe minor coding anomalies that do not have a material impact. We find that the main result on all enforcement is robust to all robustness checks: (1) randomization inference (2) alternative fixed effects and (3) multiple hypothesis testing.