The Controversial Environmental Effects of COVID-19 Lockdown on Quality of Air: Evidence from Italian Municipalities

We test the effect of the first wave COVID-19 lockdown on quality of air across Italian municipalities. We show that lockdown measures, as expected, reduced outdoor (car transit and workplace) mobility, while increasing (indoor) residential stay. We expect the first effect to contribute to better quality of air, although counterbalanced by the second due to increased heating at home. Our findings are consistent with this hypothesis, since the combined effect of lockdown measures on particulate matter concentration is nonlinear and determined by the interplay of two exogenous shocks (the lockdown decision and the nonsynchronous centralised heating halt in Italian climatic zones). More specifically, in the first lockdown month the increase in house heating generated an abnormal rise in particulate matter concentration with respect to the corresponding months of the previous years. The effect was reversed in the following two months when centralized heating halted. Evidence of the lockdown effects on mobility is consistent with the lockdown effect on outdoor mobility since we observe a significant fall in nitrogen dioxide. Policy implications of our paper is that higher ecological sustainability of heating and mobility can reduce the trade-off between economic/social activity and environmental sustainability.