Scientists have recorded a massive reduction in pollution over China during the last two months, which is believed to be a result of measures taken to stop the coronavirus outbreak.
A pair of images captured by NASA and European Space Agency pollution monitoring satellites reveal a significant change in nitrogen dioxide (NO2) levels in the air over the country between Jan. 1 and Feb. 25.
The first image, depicting the period from Feb. 1-20, features large pockets of orange and red, which represent a high density of NO2 over metropolitan areas like Beijing, Shanghai and Hong Kong.
Scientists believe the reduction in pollution over China was largely a result of measures taken to control the outbreak of the coronavirus. (Photo/NASA)
But the second image, showing the period from Feb. 10-25, reveals the majority of this pollution had disappeared completely.
The timeline for the improvement in air quality coincides with when health and government officials in China acknowledged the threat of coronavirus and put Wuhan, the epicenter of the outbreak, on lockdown.
NO2 is emitted by motor vehicles, power plants and industrial facilities - and the quarantine placed on the city shut most of these things down, likely leading to the improved air quality.
According to NASA, the reduction in NO2 pollution was first apparent near Wuhan but eventually spread across the country.
People wearing masks, play in a park in Hong Kong, Friday, Jan. 31, 2020. (AP Photo/Kin Cheung)
“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center.
The drop in nitrogen dioxide in 2020 also coincided with Lunar New Year celebrations in China and much of Asia, experts said. During this celebration, businesses and factories will often close from the last week in January into early February.
While previous observations from NASA have shown a dip in pollution during this period, it is typically followed by a return to normal levels later in the month.
“There is always this general slowdown around this time of the year,” said Barry Lefer, an air quality scientist at NASA.
A traffic policeman adjusts his mask on a street in Beijing, Sunday, Feb. 9, 2020. (AP Photo/Andy Wong)
However, the images captured by the satellites this year don't show a return to normal levels, as expected.
This failure to rebound likely means the reduction in pollution is due to measures taken to control the virus.
“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.”
China continues to host more cases of the virus than any other country globally. More than 3,300 people have died and nearly 98,000 people have tested positive for coronavirus globally, according to John Hopkins University. Only about 3.4% of the coronavirus cases have been deadly.
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