Nitrogen dioxide is a gas emitted during the combustion of fossil fuels.
It's released from the tailpipes of cars, and the smokestacks
of power plants. Together, these emissions affect the quality
of the air we breathe. Since 2004, an instrument aboard NASA's AURA
satellite has measured levels of nitrogen dioxide in Earth's atmosphere.
In 2014, we released satellite images that show how
environmental regulations have led to reductions in nitrogen dioxide
over major U.S. cities. Now, we've created a global maps
that allow us see how levels have changed around the world over the last decade.
In Western Europe, despite the recent vehicle emissions scandal
nitrogen dioxide levels have decreased by as much as 50 percent
due to tighter environmental controls. In China, we see an increase
in levels over most of the country due to a rise in coal use for power generation
but decreases for some cities, like Beijing, where a growing
middle class is now demanding cleaner air. In the Middle East, we see
decreases in nitrogen dioxide levels over Syria due to the country's
civil war and displacement of its population. Meanwhile, levels have
gone up in neighboring countries where millions of Syrians have taken refuge.
In the U.S., the only increases are in regions with intensive
oil and natural gas extraction, including fracking. In North Dakota
and Texas, we see increases of 30% in some areas.
By monitoring levels of nitrogen dioxide from space
we can see and quantify the effects of things like energy usage
environmental policy and even civil unrest on
air quality across the globe.