Table 6.

Connections with Wuhan

Treatment group	AQI
	Limited cities 2020		Limited cities 2020
Control group	Limited cities 2019		Normal cities 2020
	(1)	(2)	(3)	(4)
Treat * Post	− 0.056*	− 0.092***	− 0.036	− 0.054*
	(0.030)	(0.029)	(0.030)	(0.028)
Connections * Treat * Post	− 0.105***	− 0.088***	− 0.063*	− 0.071**
	(0.031)	(0.029)	(0.034)	(0.032)
Weather	No	Yes	No	Yes
Fixed effects	Yes	Yes	Yes	Yes
Constant	4.252***	3.869***	4.118***	3.843***
	(0.007)	(0.035)	(0.004)	(0.024)
Observations	6602	6602	13,860	13,858
R2	0.454	0.528	0.525	0.580

This table reports the impact of connections with Wuhan on the effect of lockdown policy. Column (1) and (2) compare the locked cities in 2020 to itself in 2019, and column (3) and (4) compare the locked cities in 2020 to unlocked cities in 2020. Besides, column (1) and (3) present the result with the fixed effects, and column (2) and (4) present the regression with both the weather conditions and fixed effects. The dependent variable is $\mathit{AQI}$. The key independent variable is $Connections\ast Treat\ast Post$

Significance at 10%, 5%, and 1% levels was indicated by *, **, and ***, respectively