How Coronavirus Cut Pollution - Albeit Temporarily 

China has been drawing headlines for all the wrong reasons of late. The coronavirus, first discovered there on the 31^st December 2019, has since spread all across the Asian superpower and beyond, infecting victims as far away as the UK, the USA and Australia. However, there is one unexpected boon that has arisen from the epidemic – reduced air pollution.

Satellites owned and operated by the European Space Agency (ESA) and NASA have been measuring and managing nitroxide oxides (NOx) emissions all over the globe for many years. The data they have collected in the weeks since China announced a shutdown of its central industrial powerhouses demonstrate just how much of a difference to the air quality landscape the virus has made.

Dramatic drop-off

While the Chinese authorities initially attempted to downplay the seriousness of the coronavirus outbreak, they finally acknowledged the danger on the 23^rd January 2020. From that date, the government imposed a lockdown in Wuhan city (where the outbreak originated), before enlarging the area affected by the decree to include all 16 cities located in Hubei province. A total of 57 million people were required to self-quarantine and stay indoors at all times, with only one person per household allowed to leave every two days.

While the circumstances of the lockdown were alarming and the experience is unlikely to have been a pleasant one for those affected, some positive news has come of the ordeal. The Sentinel-5 satellite (operated by the ESA) and the Aura spacecraft (controlled by NASA) both collected satellite images which demonstrated the sheer scale of the impact. Compared to the same data from 2019, pollution in and around Hubei province was virtually non-existent. With no one driving cars and no one operating factories, concentrations of both nitrogen dioxide and ozone both fell dramatically.

Not the first time

There is precedent for such a drop-off in pollution, albeit not on such a large scale. A growing market for continuous emissions monitoring systems (CEMS) has allowed Chinese authorities to paint an ever more detailed picture of the country’s air quality in recent years, and a similar reduction in NO2 and ozone were noticed during the 2008 Beijing Olympics. The global financial crash, which first erupted in 2007, also precipitated a drop-off in emissions and an improvement in air quality.

Indeed, February often sees a slump in pollution levels, as factories shut down temporarily for the Chinese Lunar New Year. However, the impact of the coronavirus means that this year’s respite was virtually unprecedented. “This year, the reduction rate is more significant than in past years and it has lasted longer,” explained Fei Liu, who works for NASA as an air quality analyst. “I am not surprised because many cities nationwide have taken measures to minimize spread of the virus.”