How much did pollution levels drop due to COVID-19 shutdowns?

Today's Video of the Day from NASA Goddard describes the use of space- and ground-based observations to examine how the COVID-19 pandemic has affected air pollution worldwide.  The scientists found that since February, pandemic restrictions have reduced global nitrogen dioxide concentrations by nearly 20 percent. Nitrogen dioxide emissions are primarily associated with traffic and industry, which were both greatly reduced during COVID-19 shutdowns. "We all knew the lockdowns were going to have an impact on air quality," said study lead author Christoph Keller. "It …