AIR-LOCK

Unprecedented lockdown measures were implemented worldwide to control the COVID-19 pandemic, leading to significant but temporary air pollution reductions. Both satellite and ground-level measurements showed substantial decreases in nitrogen dioxide (NO₂) concentrations during the lockdowns at the city or county level. In contrast, changes in fine particulate matter (PM_2.5) concentrations were inconsistent, with reductions comparable to NO₂, smaller reductions, or even increases. These disproportionate changes in ambient NO₂ and PM_2.5 pollution provide a rare opportunity for a natural experiment to address critical questions regarding the causal effects of NO₂ and PM_2.5 exposure on health.

1. To evaluate whether changes in mortality are associated with changes in ambient NO2 and PM2.5 levels before, during, and after lockdowns
2. To disentangle the short-term effects of NO2 versus PM2.5 on mortality - a challenge that has proven difficult in prior research due to the high correlation between these two pollutants

Daily cause-specific mortality data in 2015-2020 of specific regions that implemented lockdown measures leading to air pollution reductions but were not severely affected by the COVID-19 pandemic during the lockdown period: Jiangsu, China, Central and Southern Italy, Northern and Eastern Germany, and California, United States

• Yale School of Public Health, Department of Environmental Health Sciences (USA): Kai Chen, Robert Dubrow, Yiqun Ma

• Ludwig-Maximilians-Universität München, IBE-Chair of Epidemiology/Helmholtz Zentrum München, Institute of Epidemiology: Susanne Breitner-Busch, Anne Marb

• Lazio Region Health Service, Department of Epidemiology (Italy): Massimo Stafoggia, Federica Nobile

• Boston University School of Public Health (USA): Patrick Kinney