New NASA Satellite Images Reveal Air Pollution Levels in Major Cities Over the Past Decade

Although air pollution still remains a serious cause for concern across the globe, there may be some good news on the horizon--at least when it comes to U.S. cities. New NASA satellite images have shown that there's been a huge reduction of air pollution across the country over the past decade.

The Ozone Monitoring Instrument (OMI) on NASA's Aura satellite has been in orbit for the past 10 years. During that time, the instrument has measured levels of nitrogen dioxide in the atmosphere over major cities across the U.S.

Nitrogen dioxide is one of the six common pollutants regulated by the U.S. Environmental Protection Agency (EPA) to protect human health. A yellow-brown gas, it can cause respiratory problems and health issues in people. It also contributes to the formation of other pollutants, including ground-level ozone and particulates, which can also have adverse health effects.

Measurements of nitrogen dioxide from OMI depict the concentration of gas throughout a column of air in the troposphere, which is Earth's lowest atmospheric layer. The images are also color coded in order to show how concentrated the gas is; blue and green denote lower concentrations while orange and red denote higher concentrations.

Yet there's some good news when it comes to levels of these gases. Although the number of cars on the road has increased with population numbers, it seems as if air pollution has decreased. That said, the air still needs to be monitored and regulations still need to be enforced in order to continue this improvement.

"While our air quality has certainly improved over the last few decades, there is still work to do-ozone and particulate matter are still problems," said Bryan Duncan, an atmospheric scientist at NASA's Goddard Space Flight Center, in a news release.

In fact, about 142 million people still live in areas of the U.S. with unhealthy levels of air pollution. In addition, air pollution still remains a major concern in other parts of the world.

Want to see how the concentration of gas has changed in the last decade in the U.S.? You can check out interactive images on NASA's website.