Government restrictions aimed at slowing the spread of the new coronavirus appear to have led to major drops in pollution levels in parts of China and Italy.

Earlier this month, pollution-observing satellites over China discovered sharp decreases in levels of nitrogen dioxide, a gas that is mainly produced by motor vehicles, power plants and factories. The satellite data was released by the U.S space agency NASA and the European Space Agency (ESA).

"There is evidence that the change is at least partly related to the economic slowdown following the outbreak of coronavirus," NASA said in a statement.

NASA and European Space Agency (ESA) pollution monitoring satellites have detected significant decreases in nitrogen dioxide (NO2) over China. There is evidence that the change is at least partly related to the economic slowdown following the outbreak of coronavirus.

The drop in nitrogen dioxide first appeared in areas around Wuhan, the city in central China where cases of the new coronavirus were first reported in December. The pollution drops then spread across the country, NASA said.

Satellite images that NASA published online show pollution clouds had almost completely disappeared between January 1 and February 25. During this period, the Chinese government shut down transportation going into and out of Wuhan and ordered local businesses to stop operating.

"This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event," NASA air quality researcher Fei Liu said in a statement. Liu said he believes the last major drop in pollution levels over several countries came during the economic recession that began in 2008. But he said that decrease happened slowly over time.

Lauri Myllyvirta is a climate researcher with the Centre for Research on Energy and Clean Air in Helsinki, Finland. In a recent report on the pollution changes in China published in CarbonBrief, he wrote that electricity demand and industrial output remained far below their usual levels in several main areas.

Myllyvirta noted a study showing that coal usage at power plants in China was down 36 percent in the four weeks after the January 25 Lunar New Year. Oil demand fell by about 34 percent.

China's virus-fighting measures likely cut carbon dioxide (CO2) emissions by at least 25 percent during this period, the research showed.

But Myllyvirta told The Associated Press that he fears the pollution levels could see a sharp rise once the current crisis ends.

"The important question now is how China's government will respond," he said.

Myllyvirta noted that after the 2008 to 2009 financial crisis, China attempted to make up for lost economic activity by launching massive aid programs that also supported pollution-causing industries. If such assistance happens again, it "would make the environment worse long-term," he said.

In Italy, the country hit hardest by the virus outside of China, ESA satellites observed drops in air pollution as well. Pollution decreases were especially evident in northern Italy, where officials have ordered shutdowns aimed at reducing the spread of the coronavirus.

The ESA released satellite images showing clear drops in levels of nitrogen dioxide over the Po Valley area in northern Italy.

ESA's Claus Zehner is in charge of the Copernicus Sentinel-5P satellite's operations. He said in a statement it is possible that the satellite data could also have been affected by cloud cover and changing weather.

However, he added that his team is "very confident that the reduction in emissions that we can see coincides with the lockdown in Italy causing less traffic and industrial activities."