Reduction of air pollutants and associated mortality during and after the COVID-19 lockdown in China: Impacts and implications.

Although strict lockdown measurements implemented during the COVID-19 pandemic have dramatically reduced the anthropogenic-based emissions, changes in air quality and its health impacts remain unclear in China. We comprehensively described air pollution during and after the lockdown periods in 2020 compared with 2018-2019, and estimated the mortality burden indicated by the number of deaths and years of life lost (YLL) related to the air pollution changes. The mean air quality index (AQI), PM, PM, NO, SO and CO concentrations during the lockdown across China declined by 18.2 (21.2%), 27.0 μg/m (28.9%), 10.5 μg/m (18.3%), 8.4 μg/m (44.2%), 13.1 μg/m (38.8%), and 0.3 mg/m (27.3%) respectively, when compared to the same periods during 2018-2019. We observed an increase in O concentration during the lockdown by 5.5 μg/m (10.4%), and a slight decrease after the lockdown by 3.4 μg/m (4.4%). As a result, there were 51.3 (95%CI: 32.2, 70.1) thousand fewer premature deaths (16.2 thousand during and 35.1 thousand after the lockdown), and 1066.8 (95%CI: 668.7, 1456.8) thousand fewer YLLs (343.3 thousand during and 723.5 thousand after the lockdown) than these in 2018-2019. Our findings suggest that the COVID-19 lockdown has caused substantial decreases in air pollutants except for O, and that substantial human health benefits can be achieved when strict control measures for air pollution are taken to reduce emissions from vehicles and industries. Stricter tailored policy solutions of air pollution are urgently needed in China and other countries, especially in well-developed industrial regions, such as upgrading industry structure and promoting green transportation.