Source: http://gizmodo.com/a-map-of-how-much-bet...

You can literally breathe easier now; new imagery from NASA's Aura satellite shows that over the past 10 years, air quality in the U.S. has improved. It's not to say that the environment isn't still generally screwed, but that's great news, especially if you live in or near a city.

The satellite, which has spent the past decade in orbit, shows a clear reduction in nitrogen dioxide in U.S. cities. Nitrogen dioxide, for the non-NASA smarties of us, is a toxic yellow-brown gas pollutant that can give you respiratory problems.