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Air pollution drops in China after COVID-19 quarantine

A map showing the difference in air quality near Wuhan and Beijing before and after the outbreak of COVID-19. (Photo: NASA Earth Observatory)

WUHAN, China — There’s evidence of dramatic drops in air pollution across China as the country works to contain COVID-19, commonly known as the novel coronavirus.

New maps from NASA and the European Space Agency satellites show decreased levels of nitrogen dioxide in the air after the country was placed under quarantine guidelines. Nitrogen dioxide is released when fuel is burned, a practice which has decreased since the outbreak.

Officials at the NASA Earth Observatory say there is evidence that these dramatic changes are “at least partly related” to the economic slowdown which has occurred in response to the virus outbreak, according to a statement.

Maps illustrating the nitrogen dioxide levels from January and February of 2019 show the country blanketed in dark red colors — indicating higher concentrations of the gas.

However, in maps from this year the same areas are now covered in blue colors, indicating lower concentrations.

Air pollution in January and February typically drops in China, as a result of the country celebrating the Lunar New Year. But, scientists say they’re seeing a larger difference this year.

“There is always this general slowdown around this time of the year,” said Barry Lefer, an air quality scientist at NASA, in a statement. “Our long-term [Ozone Monitoring Instrument] data allows us to see if these amounts are abnormal and why.”

These monitoring instruments can distinguish between aerosol types, like smoke or dust, to measure cloud pressure and coverage, according to NASA’s atmospheric chemistry division.

NASA scientists say the typical dropoff is usually gradual and localized. It’s different this year.

“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center, said in a statement.

Liu noted it’s the steepest fall in emissions she’s seen — even more so than the 2008 economic recession. She also said it’s lasting longer than the drop in air pollution from the Olympics in Beijing the same year.

“I am not surprised because many cities nationwide have taken measures to minimize spread of the virus,” Liu said.

COVID-19 first appeared in Wuhan in December 2019. By the next month, officials quarantined the city in an attempt to stop the spread.

It was the first of several quarantines in the country, that would soon be followed around the world.

Chinese authorities began shutting down transportation going in and out of Wuhan — as well as closing local businesses — in an effort to control the virus.

All of this has curbed emissions, causing a significant drop in air pollution in the country.

This reduction of nitrogen dioxide was first seen near Wuhan, but eventually spread across the country, according to NASA.

Scientists say they hope the cleaner air will provide some relief to China as they deal with the virus, which affects the lungs. Even in the absence of COVID-19, high levels of nitrogen dioxide can inflame airways making it more difficult to breathe.