The impact of the COVID-19 outbreak on the air quality in China: Evidence from a quasi-natural experiment.

The outbreak of coronavirus (COVID-19) in early 2020 posed a significant threat to people's health and economic sustainability in China and worldwide. This study investigated whether the lockdown measures precipitated by the COVID-19 pandemic affected air pollutants in the short term. Moreover, we investigated the impact of the heterogeneity of cities and regions.