11 U.S. Cities With the Worst Air Pollution Health.com: U.S. cities with the worst air pollution we are still a long way from breathing healthy air we are still a long way from breathing healthy air cities with the worst air pollution Health.com: U.S. cities with the worst air pollution lung and other health problems 11 U.S. Cities With the Worst Air Pollution Health.com: U.S. cities with the worst air pollution