Watch a Decade of Air Pollution Disappearing Across the US

NASA's excellent visualization shows the tangible benefit of cleaner technology.

Jun 27 2014, 9:00am
Image: NASA

Air pollution continues to be a serious blight on American lungs: A 2013 MIT study found that dirty air still causes 200,000 premature deaths every year. However, we've come a long way since the coal-black skies that once pocked Pittsburgh and the nadirs of smog-choked LA. The air has been growing a little bit cleaner with every passing year.

This NASA visualization of the decline of nitrogen dioxide, one of the top six pollutants regulated by the Environmental Protection Agency, makes for a nice visualization of just how fast the air can clear. The image is based on data collected by a NASA satellite that monitored American skies for the last decade.

Image: NASA Goddard's Scientific Visualization Studio/T. Schindler

"After ten years in orbit, the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite has been in orbit sufficiently long to show that people in major US cities are breathing less nitrogen dioxide—a yellow-brown gas that can cause respiratory problems," the agency explains. Between 2005 and 2011—just a six-year period—the improvement is palpable.

The trend is certainly encouraging. NO2 is a dangerous pollutant that, according to the EPA, reacts "with ammonia, moisture, and other compounds to form small particles." Those tiny particles pose a serious risk to human health, as they "penetrate deeply into sensitive parts of the lungs and can cause or worsen respiratory disease, such as emphysema and bronchitis, and can aggravate existing heart disease, leading to increased hospital admissions and premature death."

New York's NO2 pollution levels, in 2005 and 2011. Image: NASA Goddard's Scientific Visualization Studio/T. Schindler

According to satellite data, New York's NO2 levels have fallen 32 percent since 2005; Atlanta's dropped 42 percent, and Denver's fell 22 percent. But there's improvement across the board, nationwide, too. The reason? Regulations and the improving technologies they spur. 

About half of American NO2 emissions come from dirty, fossil-fuel combustion, mostly from coal-fired power plants. The other half are spewed out in vehicle exhaust. Both have been beaten back by tighter government controls on pollution. The Clean Air Act cracked down on power plant emissions beginning in 1971, and has been steadily strengthened since then. Power plant operators have been forced to clean up their emissions by installing pollution scrubbers or switching to cleaner-burning fuels. 

Meanwhile, CAFE auto standards enacted at the federal level have required automobiles improve their fuel efficiency, which has in turn led to cleaner burning engines and less pollution. The higher standards enacted by the Obama administration in 2009 count as one of his signature environmental achievements.


These images should help drive a powerful point home about climate change, and the effort to reduce carbon emissions, too: They demonstrate that it is entirely feasible to require industry to improve its technology for the betterment of the public, without driving the economy into the ground or forcing electricity rates to skyrocket. 

Industry complains every time the EPA proposes tightening pollution controls. It will kill jobs by the truckload, they say, and usher forth ginormous electricity bills, and send the economy into a tailspin. It never does. What we get instead is tangibly, observably, and demonstrably cleaner air—and fewer premature deaths. 

There are still 142 million people impacted by too-high rates of air pollution right now, the EPA and NASA estimate. And we are only just now on the brink of beginning to regulate carbon dioxide emissions. Good thing, because thanks to climate change, that air pollution will increasingly hang in the air like a respiratory disease-causing wet blanket.

But a glance at the improvements over just the last few years is a reminder that it's not just possible to clean up our act; it's eminently doable.