Satellite images from NASA show how pollution has cleared over China as the coronavirus outbreak keeps people indoors and factories are forced to close.
NASA and the European Space Agency used pollution monitoring satellites to track the decrease in nitrogen dioxide levels over the past two months, the Daily Mail reported.
The difference in concentration of nitrogen dioxide is revealed in two maps.
The first shows large concentrations of the gas over Beijing and Shanghai in the first three weeks of January before the quarantine was in place.
A second map in the last three weeks of February reveals a startling difference with almost no nitrogen dioxide visible after China imposed a lockdown in Wuhan and other cities in the Hubei province in a bid to control the spread of the virus.
Scientists first noticed the difference around Wuhan, the epicentre of the virus, after Chinese authorities shut down transport in and out of the city as well as shutting down businesses to quarantine the outbreak.
Nitrogen dioxide is a noxious gas which is released during fuel combustion and emitted by cars, power plants and industrial facilities.
It forms when fossil fuels such as coal, gas or diesel are burned at high temperatures and can cause a range of harmful effects on the lungs including increased inflammation of the airways and a greater risk of asthma attacks.
Air quality researcher at NASA's Goddard Space Flight Center Fei Liu said: "This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event."
The drop in nitrogen dioxide also coincided with Lunar New Year celebrations across China where businesses close from the last week of January into early February to celebrate the festival.
But Ms Liu added how the reduction rate is more significant this year because it has lasted longer and there has not been an increase in nitrogen dioxide after the Lunar New Year.
Six additional maps focusing on Wuhan reveal the concentration of nitrogen dioxide over three periods including before Lunar New Year, during celebrations and after the festivities in 2019 and 2020.
While there is a drastic decrease in the levels of nitrogen dioxide in the 12 months, NASA scientist Barry Lefer added how new environmental regulations enforced by Chinese authorities over the past few years have contributed, according to Fox News.
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