With summer coming we often get ozone warnings and unhealthy air in the Pine Tree State. In a report released this week by the American Lung Association, they gave letter grades to Maine's counties for 'breathability' based on ozone levels and other factors of air quality. So how did we do?

Bangor's air quality was among the best in the United States, ranking as the fourth-cleanest in overall air quality.

Here's how each county in Maine was graded:

Aroostook: A
Penobscot: A
Washington: B
Hancock: D
Knox: B
Sagadahoc: A
Androscoggin: A
Kennebec: B
Oxford: A
York: D

Somerset, Franklin, Piscatiquis, Waldo and Lincoln counties weren't graded.

The news was good overall, as the report showed that overall air pollution levels in Maine and nationwide have dropped since the 1990's.