CLEVELAND -- A new report from the American Lung Association on Thursday shows improvement in air quality in much of the nation, but the news is not good for Cleveland.

Cleveland ranks among the worst cities in the nation for air quality. The study says Cleveland residents are being exposed to unhealthy levels of air pollution.

Experts say the city has a lot of industry, which creates pollution, and very old power plants.

The study says Ohio in general has serious and widespread air pollution problems. It's a documented issue for people who already have respiratory problems that could put them in the hospital or even kill them.

The problem can also affect relatively healthy people.

"There can be many, many more times that number who have asthma attacks, erosion of lung function that wouldn't ordinarily get detected but would have a health impact over a long period of time," said Stuart Greenberg, of Environmental Health Watch.

To help combat the air quality problem, you should avoid exercise on ozone alert days. This applies to healthy people as well.

Visit the American Lung Association's Web site for more information on the health impact of air quality and for more information on how it can be combated.