Air pollution reduction and mortality benefit during the COVID-19 outbreak in China

Abstract:

To control the coronavirus disease 2019 (COVID-19) outbreak, China adopted stringent traffic restrictions and self-quarantine measures, first in Wuhan and neighboring cities beginning Jan 23, 2020, and then 2 days later in all provinces in China. The countrywide ban on traffic mobility greatly reduced transportation emissions, whereas emissions from residential heating and industry remained steady or slightly declined. In this study, we examine the change in air pollution and the potentially avoided cause-specific mortality during this large-scale quarantine. We applied a difference-in-difference approach to quantify air pollution changes due to the quarantine. We then calculated the avoided mortality attributable to decreases in daily NO₂ and PM_2·5 over China on the basis of short-term exposure-response functions from a previous study of 272 Chinese cities. We found that, because of the quarantine, NO₂ dropped by 12.9 μg/m³ and PM_2·5 dropped by 18.9 μg/m³ across 367 Chinese cities. We estimate that improved air quality might have avoided a total of 8911 NO₂-related deaths (95% CI 6950–10 866) and a total of 3214 PM_2·5-related deaths (95% CI 2340–4087) in China from Feb 10 to March 14, 2020, had there not been a lockdown.