Post Coronavirus lockdown, NO2 pollution in China reduces whopping 10 to 30 percent, says NASA report
Satellite images from NASA show that China's polluted skies are witnessing some respite following the coronavirus outbreak.
The outbreak meant more people are staying indoors. By January 23, 2020, to curb the spread of COVID-19, Chinese authorities sealed off Wuhan and other cities, blocking transportation and shutting down local businesses. This, in turn, may have partly contributed to the decline in pollution levels, says NASA.
The images capture the falling levels of nitrogen dioxide (NO2), a foul-smelling gas emitted from cars, trucks and buses, power plants, and off-road equipment. It can cause respiratory problems like coughing, and asthma.
China saw a drop in the NO2 levels (highlighted in orange): The images show traces of the gas from February 10 to 25, compared to those released from January 1 to 20.
“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center, in a statement.
China's pollution levels have been tied to other events before. For instance, NO2 dropped during the economic recession that began in 2008 -- but the decrease was gradual, Liu explains.
Similarly, these levels dropped around Beijing during the 2008 Olympics. But once the Olympics ended, the NO2 levels shot up again.
On the other hand, researchers did expect to see a dip in pollutants at this time of the year as businesses and factories stay closed between the last week in January and early February, to celebrate the Lunar New Year. Scientists have known that air pollution usually decreases during this period and then increases once the celebration is over.
“There is always this general slowdown around this time of the year,” said Barry Lefer, an air quality scientist at NASA.
But the decline this year has more to do with the outbreak than the Lunar New Year or a weather-related change. This is because, in 2020, the NO2 values in eastern and central China were 10 to 30% lower than the previous records -- from 2005-2019.
“This year, the reduction rate is more significant than in past years and it has lasted longer,” she said. “I am not surprised because many cities nationwide have taken measures to minimize the spread of the virus.”
Falling carbon dioxide levels
According to another analysis, China has seen several changes since the outbreak: coal use at power stations is at a four-year low, levels of NO2 air pollution over China is down by 36%, compared to the same period last year and domestic flights are down up to 70%, compared to last month.
These changes may have cleared the skies off a quarter or more of the country’s carbon dioxide (CO2) emissions in early February, says a statement from Carbon Brief.
During the same period in 2019, China released around 400m tonnes of CO2. This year, however, a decrease in coal and crude oil use reduced carbon emissions of 25% or more.
Despite this, China experienced its second severe smog episode of the year last week. This could be due to steel blast furnaces, which kept functioning throughout the extended holiday, says the analysis. Besides, most power plants only shut a part of their boilers, the analysis adds.