TORONTO -- Satellite images provided by NASA show a dramatic decrease in the pollution hanging over China thanks, in part, to the economic slowdown prompted by the novel coronavirus outbreak.

When comparing satellite imagery from Jan. 1 to Feb. 25, scientists with the U.S. space agency noticed significant differences in the level of nitrogen dioxide, a gas emitted by motor vehicles, power plants and industrial facilities, over China.

“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center, said in a statement.

According to NASA scientists, the reduction in pollution was first apparent near Wuhan, the epicentre of the COVID-19 outbreak, but eventually spread across the country.

Scientists believe the dramatic decrease in pollution is “at least partly”related to the economic slowdown following the outbreak.

China has recorded nearly 80,000 cases of the virus and 2,870 deaths since early January.

Hubei Province, which includes the city of Wuhan, has been under quarantine for more than a month in an effort to contain the spread of the virus.

Nearly 50 million people have been affected by the lockdown, turning bustling cities into ghost towns.Factories across the region were also shuttered by the government during the height of the outbreak.

Although work is gradually resuming at manufacturing plants, automakers and other companies are not expected to return to full production until mid-March.

This week the stock market suffered its worst week since the 2008 recession in connection with the economic slowdown and fears that the outbreak could become a worldwide pandemic capable of causing widespread quarantines and shutting down industries.

NASA noted that China also showed a decline in nitrogen dioxide levels during the economic recession in 2008, but that decrease was more gradual.

China's Lunar New Year celebrations in late January have also been linked to decreases in pollution levels, but scientists say they normally return to average levels once the celebrations are over.

"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."