The more people that move into Colorado, the more emissions from more vehicles we get, which, unsurprisingly is making the air in Denver a lot worse.

A report by the American Lung Association moved Denver from 14th worse city in America to 12th worse in ozone pollution, citing the return of the infamous brown cloud over the city.

Known as "The State of the Air" report, it lists the cities in America with the worst and best air quality. Moving higher on the list is obviously not a good thing. But Denver is only a part of Colorado and other cities and towns in the state received better news.

Pueblo/Canon City is ranked 7th in the nation for clean air, Grand Junction is 17th in the country for clean air, while Colorado Springs is 13th.

The study breaks down the number of particulates in the air to determine the cleanliness of the air. The more items in the ozone the worse the air, which is why Denver's air has gotten worse while other areas aren't feeling the effects nearly as much.

Garfield County made the list as one of the three cleanest counties in Colorado along with Rio Blanco and La Plata Counties.