Table 1 Effects of the government policies on NO2 TVCD.

NO2 TVCD is based on OMI. We use a fixed-effects model (Eqs. 1 to 3) with the first case announced and lockdown coded as binary indicator variables. We control for the average 2015–2019 OMI NO2 TVCDs to adjust for seasonal variation and include provinces’ fixed-effects to adjust for geographical variation. The “Constant” term is the average province fixed-effect used as a baseline to compare the relative effect of the policy interventions. All SEs (shown in parentheses) are clustered at the province level.

Outcome variable
NO2 TVCD (1015 molecules/cm2)
(1)(2)(3)
First case
announced in
province, β
−1.282**−0.770*
(0.384)(0.376)
Lockdown of
province, λ
−1.073***−0.722***
(0.215)(0.151)
Average NO2
TVCD
2015–2019, δ
0.00010.004−0.001
(0.019)(0.018)(0.019)
Constant, α4.8474.4404.897
Number of
observations
102310231023
R20.5530.5550.559
Adjusted R20.5390.5400.544

*P < 0.05.

**P < 0.01.

***P < 0.001.