A blessing in disguise? - The effect of COVID-19 restrictions on air pollution in India

Sammanfattning: The outbreak of COVID-19 plunged the world economy into a pandemic with severe consequences. However, the pandemic may very well have been a blessing in disguise for the mitigation of another killer: ambient air pollution. This study investigates how the COVID-19 lockdown restrictions in India affected the ambient air pollution concentrations in a sample of Indian cities. Based on air pollution data from the World Air Quality Index, and within the framework of a sharp non-parametric regression discontinuity design, a treatment effect of the lockdown restrictions on the concentrations of PM2.5, PM10, and NO2 is estimated through local linear regressions. The results imply that the lockdown restrictions did not have a direct significant impact on air pollution levels in the full city sample. However, when accounting for heterogeneity in subsamples based on the presence of polluting industries and power stations, significant, negative reductions in PM2.5 concentrations of -29.40 and -11.97 µg/m3 are observed. The results from the local linear regressions on the full city sample are robust to changes in covariates at the cut-off where lockdown is initiated. They are not robust to a change of the interval around the cut-off and the use of a linear regression model, possibly due to the presence of a low number of mass points in the forcing variable.