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.
At the end of 2019, medical professionals in Wuhan, China, were treating dozens of pneumonia cases that had an unknown source. Days later, researchers confirmed the illnesses were caused by a new coronavirus (COVID-19). By January 23, 2020, Chinese authorities had shut down transportation going into and out of Wuhan, as well as local businesses, in order to reduce the spread of the disease. It was the first of several quarantines set up in the country and around the world.
The maps on this page show concentrations of nitrogen dioxide, a noxious gas emitted by motor vehicles, power plants, and industrial facilities. The maps above show NO2 values across China from January 1-20, 2020 (before the quarantine) and February 10-25 (during the quarantine). The data were collected by the Tropospheric Monitoring Instrument (TROPOMI) on ESA’s Sentinel-5 satellite. A related sensor, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, has been making similar measurements.
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Image via NASA Earth Observatory