Effect of Air Pollution Reductions on Mortality During the COVID-19 Lockdowns in Early 2020

This report, available for downloading below, presents a study led by Kai Chen of the Yale School of Public Health. Chen and colleagues used the unique scenario of COVID-19 lockdowns in early 2020 to understand how a pause in human activity might affect day-to-day changes in air pollution and the resulting effects on health.

The investigators conducted their study in four regions that covered an entire country (Germany) or part of a country (California in the United States, Central and Southern Italy, and the coastal eastern region of Jiangsu, China). These areas were selected because high-quality data on air quality and health outcomes were available and because the areas had lockdowns early in the COVID-19 pandemic, before their populations were substantially affected by COVID-19 deaths or disruptions of the healthcare system.

Key takeaways from the study:

• Nitrogen dioxide and fine particulate matter concentrations were lower during the lockdowns than in pre-lockdown reference periods in regions of China, Italy, and the United States, even after accounting for weather and trends. During the lockdown in Germany, nitrogen dioxide concentrations were essentially unchanged, and concentrations of fine particulate matter increased.
• Before the pandemic, all-cause, natural, and cardiovascular deaths were higher on days with higher concentrations of nitrogen dioxide and fine particulate matter. Changes in air pollution during COVID-19 lockdowns indicated that fewer air pollution-related deaths would result where the air quality improved.
• The study demonstrated that changes in human activity, whether planned or unforeseen, can reduce air pollution, with potential benefits to health.