If you get depressed about the plethora of news about environmental woes, here’s a bit of news that should make you breathe easier.

NASA has just released new images from its Aura satellite, which was launched back in 2004 to study the chemistry of the Earth’s atmosphere. They show that over the past decade, the amount of nitrogen dioxide -- a yellow-brown gas produced by gasoline-burning car engines and coal-burning electrical power plants that can cause respiratory problems -- has decreased. That’s true, even though the U.S. population has increased and there are more cars on the road.

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The satellite observations show that even New York City, the most densely populous area in the United States, is making major progress in reducing N02 pollution. The city that never sleeps has been working aggressively over the past decade to monitor and reduce air pollution.

In the late 2000s, New York began mounting portable air-sampling devices on light poles in all five boroughs. Last year, the city began a pilot program to test quick-charging electric-powered taxis.

Satellite data shows a 32 percent decrease in nitrogen dioxide levels over New York City since the mid-2000s. Credit: NASA

Another apparent reason for the decline is the ongoing federal and state regulatory efforts to reduce emissions from power plants. A study by Duke University researchers, published this week in the International Journal of COPD, found that in North Carolina, such controls have resulted in a substantial decline in deaths from respiratory illnesses such as asthma and emphysema.

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Nitrogen dioxide is one of six common air pollutants regulated by the U.S. Environmental Protection Agency, which this year began requiring states and local governments to monitor for levels of the gas.

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