New Delhi | Jagran Lifestyle Desk: Coronavirus pandemic-induced restrictions reduced the global nitrogen dioxide concentration by nearly 20 per cent since February, NASA researchers have found.

While the space and ground-based observations had earlier shown that the Earth's atmosphere saw reductions in some air pollutants, it had remained unclear as to how much of the decline could be attributed to change in human activity amid the restrictions imposed world-wide to contain the spread of virus.  

To quantify how much of that change was attribute to the lockdowns, the researchers used computer models to generate a COVID-free 2020 for comparison, NASA said in a statement.  

"We all knew the lockdowns were going to have an impact on air quality," said lead author Christoph Keller. "it was also soon clear that it was going to be difficult to quantify how much of that change is related to the lockdown measures, versus general seasonality or variability in pollution. 

To derive the results, researchers could not have simply compared 2020 nitrogen dioxide concentrations with data from 2019 and 2018, since normal variations in weather and atmospheric circulation change the chemistry of the atmosphere. Hence, Keller and his team accounted for COVID-19 by having the NASA model ignore the pandemic altogether. 

"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." 

Industrial activities and transportation were virtually halted during lockdowns imposed in several countries across the globe as part of the measures to contain the spread of coronavirus.  

Posted By: Lakshay Raja