Severe changes were noticed on Earth as the COVID-19 pandemic left the humans locked inside their homes. A newly observed one maps the levels of nitrogen dioxide (NO2) across the globe during the time and as it turns out, the concentration of the air pollutant went down significantly.
The?observation?has been recorded by researchers at the?NASA?Center for Climate Simulation using model simulation and machine learning analysis. The researchers found that the?COVID-19 pandemic restrictions, in effect since February, have resulted in a reduction of global nitrogen dioxide (NO2) concentrations by as much as 20 percent.
Nitrogen dioxide is one of the?major air pollutants?and is primarily produced by the combustion of?fossil fuels?used by industry and transportation. It was hence, important to map the level of this change that was brought about solely by the restriction on human activities.
For this, scientists at NASA compared the concentrations of nitrogen dioxide recorded during the pandemic to a simulated model for the year wherein the pandemic never really took place. In the latter model, human activities were imagined to be conducted as always and the global NO2 concentrations were simulated accordingly.
The difference could hence be used to map the exact effect of reduction in human activities during the pandemic on the level of air pollution across the globe.
"We all knew the lockdowns were going to have an impact on air quality," said study lead author Christoph Keller with Universities Space Research Association (USRA) at NASA's Goddard Space Flight Center in the US.
For the real readings during the year, NASA recorded data from 46 countries through a total of 5,756 observation sites on the ground. These sites relayed hourly atmospheric composition measurements in near-real-time.
NASA observed that on a city-level, 50 of the 61 analysed cities experienced a reduction in nitrogen dioxide to the amount of 20-50 percent.
¡°In some ways I was surprised by how much it dropped," said Keller.
"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 behaviour-driven contribution," Keller added.