When the world went into lockdown to slow the spread of COVID-19, emission of pollutants into the atmosphere plummeted.
A team of international researchers led by scientists at NASA’s Jet Propulsion Laboratory charted the drop in emissions
and how it impacted global air pollution and the climate system.
The study found that levels of nitrogen oxides (NOx), which react to form surface-level ozone, globally decreased by 15%.
This drop in NOx resulted in a 2% global drop of ozone near Earth's surface.
Ozone high in the upper atmosphere protects us from destructive solar radiation.
But when it's closer to the ground, ozone is harmful to human health.
While a 2% drop may seem small, this drop in ozone, which occurred over 8 months,
would take 15 years to achieve under even aggressive emission control scenarios.
Ozone depends on a number of factors and not just NOx emissions alone,
which is why the team pulled together a variety of air quality measurements
and combined them with a computer model to understand what happened.
This map, created using measurements of atmospheric gases from NASA and European Space Agency Earth-observing satellites,
shows where ozone reductions occurred worldwide.
The results of the study imply that both NOx emissions and ozone near Earth's surface will climb again as the global economy opens up.
However, the study provides a unique glimpse into a future with better global air quality. This future could be achieved with
sustainable measures that could improve both human health and climate.