NASA satellites helped create this animated GIF showing air pollution drop between 2005 and 2011. You can see the biggestconcentrations (specifically nitrogen dioxide) around Chicago and the Northeast Corridor, but thanks to airpollution regulations for cleaner cars and coal-burning power plants, alongwith improved technologies, we’re all seeing cleaner air even though the number ofcars on the road has increased. Yay! Three cheers for good news on theenvironment! (Psst. In case this left you feeling too good, you can insteadworry about high power plant emissions of carbon dioxide, a greenhouse gas.)