The American Lung Association says 60 percent of Americans live in areas with unhealthy air pollution levels.

The group ranked pollution levels of U.S. cities and counties based on data collected by the Environmental Protection Agency between 2005 and 2007. The report suggests air pollution at times reaches unhealthy levels in almost every major city.

The association says more than 180 million people live in "areas where the air can be dirty enough to send people to the emergency room, dirty enough to shape how kids' lungs develop and even dirty enough to kill."

Los Angeles and its surrounding areas had the highest levels of
ozone pollution, as they have in each of the past 10 reports.

The silver lining on the pollution cloud? Cities including Charlotte, Los
Angeles, New York, Atlanta, Philadelphia, Washington D.C. and Baltimore have seen improvements in air quality over the last decade.