AUGUSTA — A report released Wednesday says Maine’s air quality is better than it was a year ago, but it also finds room for improvement.

The American Lung Association’s report says ozone levels improved by one or two grades in all counties, and unlike last year, no Maine county got a failing grade.

Aroostook County went from C to A in ozone pollution and ends up as one of the cleanest counties in the country in that category. At the other end of Maine, York County nudged up to D from F.

Because of its location as a receiver of pollutants from other states, Maine is sometimes called the nation’s “tail pipe.”

The lung association’s Ed Miller says Maine’s senators are critical to preventing a weakening for the federal Clean Air Act.