Are you breathing dirty air? A lot of Americans still are, according to a new American Lung Association report.

FOX's Rachel Sutherland reports: 

The report finds while air quality continues to improve nationwide, 52% of people in the United States still live in areas with unhealthy levels of air pollution. The most polluted air in the nation is in Bakersfield, California, which has the most unhealthy days from airborne particles belched by diesel trucks, farm equipment and general highway traffic.

Los Angeles has the worst ozone pollution. The city with the cleanest air based on year-round particle pollution is Farmington, New Mexico.

In Washington, Rachel Sutherland, FOX News.