A new report on air quality across the U.S. offers a cloudy prognosis on the long-term health of about 156 million residents who live in areas that received an "F" in smog and soot pollution.

American Lung Association report found that about 156 million people live in counties plagued by high levels of ozone and fine particulate matter

About 46% of U.S. residents — 156 million people — lived in areas with unhealthy air quality that earned “F” grades from the American Lung Association for ozone or particle pollution.