Pittsburgh, Pa., has received the dubious honor of being the U.S. city most well-sooted for short-term particle pollution, topping an annual list put out by the American Lung Association. Los Angeles came in at a surprise second as Pittsburgh became the first non-California city to top an ALA list. “It’s not that Pittsburgh has gotten worse,” says the association’s Janice Nolen. “It’s that Los Angeles has gotten better.” A little better, anyway: L.A. was still deemed the worst city for ground-level ozone and for year-round particle pollution (Pittsburgh was the runner-up on that list). Overall, some 42 percent of the American population has unhealthy exposure to ozone and/or soot, according to the report. Want to breathe clean air? Fargo, N.D., beckons.