Most of the world has dirty air, with just 17% of global cities meeting WHO air pollution guidelines, a report Tuesday found.

The majority of the world is breathing in dirty air, according to the latest air quality report. So where does the U.S. rank?

Breathing in polluted air over a long period of time can cause respiratory illness, Alzheimer’s disease and cancer ... cities like Beijing, Seoul, South Korea, and Rybnik in Poland have ...