According to a study led by scientists at NASA’s Jet Propulsion Laboratory, emissions of nitrogen oxides (NOx), a hazard to human health and the climate, decreased by 15% globally, with local reductions of up to 50% , as the coronavirus pandemic slowed global trade in early 2020.
The study was dedicated to investigating the two main nitrogen oxides: nitrogen oxide and nitrogen dioxide, collectively referred to as NOx. The researchers used measurements of NOx, ozone and other atmospheric gases from five Earth-observing satellites from NASA and ESA .
Where confinement was stricter, levels dropped much lower. For example, in China, in early February 2020, there was a 50% drop in NOx emissions in some cities within a few weeks. And most states in the United States achieved a 25% drop later in the spring .
Ozone reductions from reduced NOx emissions spread rapidly around the world and from the surface upward more than 10 kilometers.
The overall result of reduced NOx emissions was a 2% drop in global ozone , half the amount expected to be produced by the most aggressive NOx emission controls considered by the Intergovernmental Panel on Climate Change.
These findings indicate that both global NOx emissions and ozone will rise again as the world economy accelerates again.