COVID-19 lockdown reduced global NO2 concentrations by nearly 20%: NASA

As world was clamped down under lockdown to stem spread of vel coronavirus, researchers at NASA found that global Nitrogen dioxide (2) emissions drastically reduced by nearly 20 percent. Using computer-based models, scientists have found that hazardous air pollutant, primarily emitted into atmosphere due to fossil fuel combustion by transportation and commercial industries,  significantly declined since February 2020. This was around time when world was hit by first pandemic wave and many countries imposed stay-at-home orders and shuttered businesses to curb COVID-19 transmission. 

“We all knew lockdowns were going to have an impact on air quality,” said lead author Christopher Keller with Universities Research Association (USRA) at NASA’s Goddard Flight Center in Greenbelt, Maryland, in a NASA release.

Furr, researcher Christopher Keller said, “It was also soon clear that it was going to be difficult to quantify how much of that change is related to lockdown measures, versus general seasonality or variability in pollution.” A researcher at NASA’s Goddard Global Modeling and Assimilation Office (GMAO), Kelly was a part of team that conducted research using high-tech computer models that help track chemistry of ocean and atmosphere and forecast climatic changes. 

[Nitrogen dioxide levels often dip during Lunar New Year celebrations in China and much of Asia, and n rebound. But rebound was evident this year over Wuhan, China where virus was first reported, and nitrogen dioxide levels remained much lower than in 2019. Credit: NASA's Earth Observatory]

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NASA model projections

Scientists at NASA measured percent of nitrogen dioxide concentrations in atmosphere with help of NASA model projections. Comparing it with emission in previous years, y estimated change in atmospheric composition caused by COVID-19 containment across globe. “re was predicting sudden, drastic shifts in human behaviour as vel coronavirus—and regulations attempting to control it,” researchers said in a release. y conducted study using model simulation and machine learning to subtract simulated values and measured ground observations at NASA Center for Climate Simulation to achieve findings. 

“Many countries have already done a very good job in lowering ir nitrogen dioxide concentrations over last decades due to clean air regulations, but what our results clearly show is that re is still a significant human behavior-driven contribution,” Kelly said in a release.

Data from at least 46 countries were used, including a total of 5,756 observation sites. In at least 50 of 61 cities that were used for emission analysis, a significant reduction in nitrogen dioxide’s release, between 20-50 percent, was ted. “In some ways, I was surprised by how much it dropped,” said Keller. 2 emission was dropped to 60 percent lower than simulated values, a 60 percent decline was found in Milan, and a 45 percent decrease in New York. 

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