These two maps show typical nitrogen dioxide levels over China from January 1-20, 2020, and then show decreased nitrogen dioxide levels over the same area from February 10-25, 2020.

Credit: Josh Stevens/NASA Earth Observatory

The 2020 COVID-19 shutdown resulted in decreased levels of nitrogen dioxide (NO2) pollution over China due to fewer vehicles on the road. It is important to note that while NO2 pollution did improve, this does not mean that overall air quality in China, which is frequently at unhealthy levels, was improved enough to be considered healthy during this time.