Air pollution changes due to COVID-19 lockdowns and attributable mortality changes in four countries

Area of Science:

• Environmental Science
• Public Health
• Epidemiology

Background:

• COVID-19 lockdowns led to widespread reductions in air pollution, including nitrogen dioxide (NO2) and fine particulate matter (PM2.5).
• Assessing the health impacts of these pollution changes is crucial for understanding the broader consequences of such public health interventions.

Purpose of the Study:

• To quantify changes in NO2 and PM2.5 concentrations during COVID-19 lockdowns in Jiangsu, China; California, U.S.; Central-southern Italy; and Germany.
• To assess the attributable changes in mortality resulting from these air quality improvements.

Main Methods:

• Utilized a machine learning-based meteorological normalization technique and the difference-in-differences approach to isolate lockdown-induced pollution changes.
• Employed region-specific estimates from causal modeling (2015-2019) to link air pollution changes to mortality outcomes.

Main Results:

• Significant reductions in NO2 concentrations during lockdowns were associated with avoided mortality in Jiangsu, California, and Central-southern Italy.
• PM2.5 reductions also yielded mortality benefits, though generally smaller in magnitude.
• Germany experienced non-significant mortality benefits from NO2 changes and an increase in mortality linked to higher PM2.5 levels.

Conclusions:

• COVID-19 lockdowns generally improved air quality and provided attributable health benefits, primarily linked to NO2 reductions.
• Significant regional heterogeneity exists in the air quality and mortality impacts of lockdowns.
• Policymakers must consider local characteristics when adapting emission control strategies from other regions.