Table 2.

Baseline results

Treatment group	AQI
	Locked cities 2020		Locked cities 2020
Control group	Locked cities 2019		Unlocked cities 2020
	(1)	(2)	(3)	(4)
Panel A: AQI
Treat * Post	− 0.135***	− 0.159***	− 0.083***	− 0.106***
	(0.020)	(0.019)	(0.016)	(0.015)
Weather	No	Y	No	Y
Fixed effects	Y	Y	Y	Y
Constant	4.252***	3.864***	4.118***	3.843***
	(0.007)	(0.035)	(0.004)	(0.024)
Observations	6602	6602	13,860	13,858
R2	0.453	0.527	0.525	0.580
Panel B: PM2.5
Treat * Post	− 0.247***	− 0.241***	− 0.114***	− 0.140***
	(0.025)	(0.024)	(0.020)	(0.019)
Weather	No	Yes	No	Yes
Fixed effects	Yes	Yes	Yes	Yes
Constant	3.818***	3.257***	3.661***	3.199***
	(0.009)	(0.044)	(0.005)	(0.029)
Observations	6602	6602	13,860	13,858
R2	0.449	0.545	0.550	0.618
Panel C: NO2
Treat * After	− 0.359***	− 0.382***	− 0.140***	− 0.160***
	(0.016)	(0.016)	(0.014)	(0.013)
Weather	No	Yes	No	Yes
Fixed effects	Yes	Yes	Yes	Yes
Constant	3.321***	3.104***	3.036***	2.804***
	(0.006)	(0.029)	(0.003)	(0.019)
Observations	6602	6602	13,860	13,858
R2	0.691	0.736	0.709	0.751

This table reports the impact of the lockdown policy on air pollution. 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 $\mathit{AQI}$, $PM2.5$ and $N{O}_2$ in panel A, B and C, respectively. The key independent variable is $Treat\ast Post$

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