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NASA and European Space Agency (ESA) data show a dramatic decline in pollution levels over China.
The US space agency believes this is “partially related” to an economic slowdown due to coronavirus.
NASA and European Space Agency (ESA) pollution monitoring satellites have detected significant reductions in nitrogen dioxide (NO2) over China.
Due to the containment measures of the novel coronavirus in China taken on January 23, 2020, pollution levels have significantly decreased compared to the previous year.
The maps show the concentrations of nitrogen dioxide across China, a harmful gas emitted by vehicles, power plants, and industrial plants from 1 to 20 January 2020 (before the quarantine) and from 10 to 25 February (during the quarantine). Data were collected by the Tropospheric Monitoring Tool (TROPOMI) on ESA’s Sentinel-5 satellite. A related sensor, the Ozone Monitoring Tool (OMI) on NASA’s Aura satellite, made similar measurements. The 2020 values are compared with the same periods in 2019 for reference.
Launched in 2004, OMI has been collecting global data on NO2 and various air pollutants for over 15 years.
According to NASA scientists, the reduction of NO2 pollution was initially noticeable around Wuhan. As the days passed, the reduction spread across the country.
“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. Liu recalls seeing a drop in NO2 in several countries during the economic downturn that started in 2008, but the decline has been gradual.
The reduction in pollution levels in 2020 also coincided with the lunar new year celebrations in China. During this period, companies and factories close from the last week of January to early February to celebrate the festival. Previous observations have shown that air pollution usually decreases during this period and then increases at the end of the celebration.
Featured image: Fog in Shanghai