Airborne Pollution Plummets Over China

choi

Airborne Nitrogen Dioxide Plummets Over China, NASA, Feb 28, 2020
https://earthobservatory.nasa.go ... plummets-over-china
("NASA and European Space Agency (ESA) pollution monitoring satellites have detected significant decreases in nitrogen dioxide (NO2) over China. * * * 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.  According to NASA scientists, the reduction in NO2 pollution was first apparent near Wuhan, but eventually spread across the country. * * * Fei Liu, an air quality researcher at NASA's Goddard Space Flight Center * * * recalls seeing a drop in NO2 over several countries during the economic recession that began in 2008, but the decrease was gradual. Scientists also observed a significant reduction around Beijing during the 2008 Olympics, but the effect was mostly localized around that city, and pollution levels rose again once the Olympics ended.  The drop in nitrogen dioxide in 2020 also coincided with Lunar New Year celebrations in China and much of Asia. Generally, businesses and factories close from the last week in January into early February to celebrate the festival. Past observations have shown that air pollution usually decreases during this period and then increases once the celebration is over")