Watch how a dangerous air pollutant dropped during coronavirus pandemic in NASA video
NASA discovered that global nitrogen dioxide (NO2) concentrations have dropped by nearly 20% since February, when the coronavirus pandemic started severely altering human activity.
It’s a trend researchers were aware of in a handful of cities earlier in the pandemic, but now NASA has a video that shows how levels of the dangerous air pollutant have fluctuated over time.
Using space- and ground-based observations along with computer models, scientists with NASA’s Center for Climate Simulation wanted to learn how much of that reduction in pollution was tied to changes in transportation and combustion activity from the fossil fuel industry.
So, the team compared two models — one of current 2020 measurements and another of a “COVID-free 2020” — that accounted for natural variations in weather and atmospheric circulation that influence air chemistry, according to a news release.
They found that 50 of the 61 cities across the world they analyzed experienced drops in NO2 levels between 20% and 50%.
“In some ways I was surprised by how much it dropped,” lead researcher Christoph Keller, who works with the Universities Space Research Association at NASA’s Goddard Space Flight Center in Maryland, said in the release. “Many countries have already done a very good job in lowering their nitrogen dioxide concentrations over the last decades due to clean air regulations, but what our results clearly show is that there is still a significant human behavior-driven contribution.”
What’s more, the scientists found that decreases in NO2 levels aligned “shockingly well” with decreases in economic numbers.
“We would expect them to be somewhat related because nitrogen dioxide is so closely linked to economic activities, like people who travel and factories running,” Keller said. “It looks like our data captures this very well.”
NO2 is emitted into the air after the burning of fossil fuels such as diesel, gasoline and coal, according to NASA, and it also comes out of tailpipes when driving cars and smokestacks when generating electricity.
That’s why changes in NO2 levels can paint an accurate picture of what human activity looks like.
High concentrations of the gas can irritate humans’ respiratory systems and aggravate diseases such as asthma, the U.S. Environmental Protection Agency says.
It can also interact with other chemicals in the air to form acid rain, which harms ecosystems such as lakes and forests, and can make the air cloudy, ruining precious views that can be seen from national parks, the EPA says.
NASA scientists received data from 46 countries that provided hourly atmospheric composition measurements in “near-real time.”
Wuhan, China, where COVID-19 first emerged, was the first to show declines in NO2 — “60% lower than simulated values expected,” researchers said.
A 60% decrease was also found in Milan, Italy, and a 45% drop was reported in New York, two regions that experienced coronavirus outbreaks shortly after China.
But once restrictions eased, the decreases “lessened, but remained below expected ‘business as casual’ values,” according to NASA.
The results of the research were presented at the 2020 International Conference for High Performance Computing, Networking, Storage and Analysis.
This story was originally published November 24, 2020 at 1:05 PM with the headline "Watch how a dangerous air pollutant dropped during coronavirus pandemic in NASA video."
