Pollution levels have plummeted over China and it's "partly related to the economic slowdown following the outbreak of coronavirus," NASA said in a statement accompanying the release of satellite images demonstrating the nitrogen dioxide (NO2) changes.

Driving the news: The outbreak caused China's factory activity to fall to a record low of 35.7 in February from 50.0 in January, officials said Saturday, per the Financial Times. NO2, a key contributor to smog and a major health hazard, is the gas that's emitted by motor vehicles, power plants and other industrial facilities.

NO2 levels in Wuhan, China, the epicenter of the outbreak. Photo: NASA

This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event."

— Fei Liu, air quality researcher at NASA’s Goddard Space Flight Center

Zoom in: NASA scientists first noticed the reduction in NO2 pollution in January near Wuhan, the epicenter of the COVID-19 outbreak. They then noticed changes in pollution levels across the country as the virus spread.

The big picture: Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center, recalled seeing a fall in NO2 levels over several countries during the economic recession that began in 2008, but that was more gradual.

Lunar New Year celebrations may have contributed to the big drop, but Liu noted the levels had not rebounded — as happened when there was a dip in Beijing during the 2008 Olympics before they rose again after the Games finished.

"This year, the reduction rate is more significant than in past years and it has lasted longer," Liu said. "I am not surprised because many cities nationwide have taken measures to minimize spread of the virus."

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