The coronavirus-induced restrictions around the world significantly reduced pollutants produced by the combustion of fossil fuels, NASA researchers have found. They used computer models to generate a COVID-free 2020 for comparison purposes and concluded that pandemic restrictions, which led to a reduction in the use of fossil fuels by industry and transportation, subsequently reduced global nitrogen dioxide concentrations by nearly 20 per cent.

The NASA report was based on data collected from 46 countries. Hourly atmospheric composition measurements from over 5,000 observation sites were studied by NASA experts. They found that 50 of the 61 cities they studied saw 20-50 per cent reduction in nitrogen dioxide levels. “The results were presented at the 2020 International Conference for High-Performance Computing, Networking, Storage, and Analysis,” said a NASA report. NASA researcher Christoph Keller, who was the project lead, said in a statement that everyone knew “the lockdowns were going to have an impact on air quality” but it was difficult to “quantify how much of that change is related to the lockdown measures, versus general seasonality or variability in pollution”.

The report suggests that Wuhan, the first epicentre of the coronavirus outbreak, was also the first to show reduced nitrogen dioxide emissions. The study showed 60 per cent lower emissions than simulated values expected. As the restrictions were imposed in Milan and New York, the cities recorded a 60 per cent and a 45 per cent decrease respectively. Emma Knowland, a co-author, stated that at times, a decrease in air pollutants was recorded even before the official policies went into place. Knowland opined that people were probably reducing their transit because the talk of the Covid-19 threat was already happening before they were actually told to shut down.

As per NASA findings, China’s Wuhan, which was the epicentre of the coronavirus pandemic outbreak and was the first to impose a lockdown, showed the first reduction in emission level – it was as much as 60 per cent lesser than expected. The other region that showed a similar reduction in nitrogen dioxide emissions was Milan. Meanwhile, in New York, which was for long the worst-affected city in the US, pollution levels declined by 45 per cent.