China’s lockdown measures to minimize further coronavirus infections have created one unexpected benefit — a dramatic improvement to the nation’s air quality. Satellites operated by NASA and the European Space Agency have detected significant drops of major airborne pollutants above vast swathes of the country.
Before-and-after images show how nitrogen dioxide levels plummeted in February compared to pre-lockdown January of this year. Nitrogen dioxide is a noxious gas emitted by factories, motor vehicles and fossil fuel-powered electricity generation stations. The data were collected by ESA’s Sentinel-5 satellite. Ozone measurements from NASA’s Aura spacecraft showed similar results.
NASA scientists first detected the decline of pollutants near Wuhan in Hubei province. A food market in the city is believed to be the epicenter of the novel coronavirus outbreak, which has since spread to more than 50 countries.
A comparison of nitrogen dioxide levels above China in early 2019 and early 2020.
“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.