Coronavirus quarantine dramatically improves air quality in China


Dozens of plants have been temporarily shut down across China to try to stop the spread of the virus, with more than 80,000 confirmed cases in the country. This has had an unexpected side effect with the virus, but it has a significant impact on the quality of life in all polluted cities in China.

Credit to NASA

The satellites of the North American (NASA) and European Space Agency (ESA) in recent weeks have found a "significant" drop in nitrogen dioxide (NO2) levels in Chinese airspace. The decline may be linked, at least in part, to economic slowdown after the emergence of coroviral disease.

According to NASA scientists, the reduction in NO2 pollution was "obvious" for the first time near Vaughan, where the virus was first reported, but eventually spread throughout the country. In January, transport was shut down to Vaughan and local businesses.

"This is the first time I see such a dramatic fall in such a wide area for a particular event," said Faye Liu, air quality researcher at the Goddard Space Flight Center at Nasa Air. Liu remembers seeing a drop in NO2 in several countries during the economic recession that began in 2008, but the decline has been gradual.

The fall in nitrogen dioxide also coincided with the lunar New Year celebrations in China and much of Asia. Generally, companies and factories close to the last week of January, beginning of February, celebrate the festival. Previous observations have shown that air pollution generally decreases during this period, and then increases when the holiday is over.

"There is always a general slowdown during this time of year," said Barry Leffer, a NASA air quality scientist. "Our IMO long-term data allows us to see whether these funds are abnormal and why." Launched in 2004, IMO has been collecting global data on NO2 and various air pollutants for more than 15 years.

While the lunar New Year may have played a role in the last fall, researchers believe that the drop is more than just a festive effect or weather changes. According to a preliminary analysis, NASA researchers compared the NO2 values ​​found by IMO in 2020 to the average values ​​found during this time period 2005-2019.

Credit to NASA

NO2 values ​​in eastern and central China are significantly lower (10% to 30% lower) than typically observed during this period, according to NASA. In addition, Liu and his colleagues have not seen a decrease in vacancy after resting in NO2.

"The rate of decline this year is more significant than in previous years and has continued for longer," he said. "This is not surprising because many cities across the country have taken steps to reduce the spread of the virus."

According to the Carbon Brief, Coronavirus temporarily reduced China's CO2 emissions by a quarter. The climate website says electricity demand and industrial production are "much lower" in many respects. Coal use is four years low and steel production lines are the lowest in five years, by the way.

Many parts of Chinese cities (including large cities) have very poor air quality, according to a recent World Air Quality Report. However, they have recently shown improvement with a 9% decrease in pollutant concentration compared to last year.