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  • Liza K. Tóth

Dramatic Pollution Reduction in China!


NASA Earth Observatory images by Joshua Stevens, using modified Copernicus Sentinel 5P data processed by the European Space Agency.


Dramatic pollution reduction in China is associated with Coronavirus quarantine: What questions are raised?


Nitrogen Dioxide (NO2) is a noxious gas emitted by motor vehicles, power plants, and industrial facilities. Air with a high concentration of NO2 can irritate airways in the human respiratory system, leading to and aggravating respiratory diseases, particularly asthma, coughing, wheezing and difficulty in breathing. Such problems can result in hospital admissions and visits to emergency rooms.


NASA’s Image of the Day for March 2, 2020 shows the extent to which NO2 amounts have dropped with the coronavirus quarantine, from January 1 to February 25, 2020. These images were taken by NASA and European Space Agency (ESA) satellites, and show the NO2 density values across China from January 1-20, 2020 (before the quarantine) and from February 10-25 (during the quarantine).


There is evidence that the change is at least partly related to the economic slowdown following the outbreak of coronavirus. Millions of people in China have been quarantined in response to the virus, detected in at least 56 countries by the end of February 2020. According to NASA scientists, the drop in NO2 levels was first noticed near Wuhan, the epicentre of the virus, and then 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 air quality researcher Fei Liu, at NASA’s Goddard Space Flight Center.


The drop in pollution also coincided with Lunar New Year celebrations. While past observations have shown that air pollution in China generally decreases during this period, it normally rebounds once the celebrations are over. However, this year there was no rebound after the holiday. According to Liu, “This year, the reduction rate is more significant than in past years and it has lasted longer. I am not surprised because many cities nationwide have taken measures to minimize spread of the virus.”


We now have experiential proof that reduction in industrial activity can bring about surprisingly swift reduction in pollution levels. What are the further implications of this data for the planet and its economy? Do these photos pose more questions than answers?


For example:

  • Is there a set of trade-offs that would allow an acceptably modern material standard of living across the planet to co-exist with a dramatically reduced pollution profile?

  • If energy sources were to be changed to non GHG-emitting alternatives, such as nuclear power, would we benefit from like improvements while maintaining a similar level of economic input?

  • Even with current energy sources, would reduction in demand, based on giving up things we don’t really need, translate to similar reductions in pollution?

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