Improvement of the Global Air Quality: the Bright side of the COVID-19 Pandemic

Abstract:

In response to COVID-19 pandemic, most of the countries have issued countrywide shelter-in-place, stay-at-home, closure, shutdown orders, and border control measures. This study investigated the impacts of the global response to COVID-19 on air pollution and air quality changes in major cities across the globe over the past few months. Air quality data (NO₂, CO, PM_2.5, and O₃) were collected from the World Air Quality Index Project (https://waqi.info/) for January 2019-April 2020 period. Results show a significant reduction in the levels of 2020 NO₂, CO, and PM_2.5 compared to their levels in 2019. These reductions were as high as 63% (Wuhan, China), 61% (Lima, Peru), and 61% (Berlin, Germany), in NO₂, CO, and PM_2.5 levels, respectively. In contrast, 2020 O₃ levels increased substantially, as high as 86% (Milan, Italy), in an apparent response to the decrease of titration by nitrous mono-oxides and its derivatives. Significant differences in the weather conditions across the globe do not seem to impact this air quality improvement trend. Will this trend in the reduction of most air pollutants to unprecedented levels continue in the next few weeks or even months? The response to this and other questions will depend on the future global economic and environmental policies.