NASA released satellite images taken in conjunction with the European Space Agency's pollution monitoring satellites that show a significant decrease in nitrogen dioxide (NO2) over China. The agency reported that the reduction of nitrogen dioxide was due to the outbreak of the coronavirus.
Nitrogen dioxide is a noxious polluting gas emitted by vehicles, power plants, and industrial facilities. As China shuts down businesses and traffic, the gas is no longer present. The images presented as maps show NO2 values across China from before the quarantine (January 1-20, 2020) and during the quarantine (February 10-25).
A dramatic drop
“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said in a statement Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center.
There was also another reason for the drop in nitrogen dioxide and that is the Lunar New Year celebrations that take place in China and much of Asia. Due to these holidays, businesses and factories close from the last week in January into early February. This results in a decrease of pollution that has also been reported in past observations.
“There is always this general slowdown around this time of the year,” said Barry Lefer, an air quality scientist at NASA. “Our long-term OMI data allows us to see if these amounts are abnormal and why.”
However, the researchers note that the new decrease has been more significant than in past years and there has been no rebound after the holiday. As such, they attribute the drop in pollution levels to the coronavirus quarantines.
“This year, the reduction rate is more significant than in past years and it has lasted longer,” Liu said. “I am not surprised because many cities nationwide have taken measures to minimize the spread of the virus.”