Bakersfield had the worst level of fine-particle pollution in the nation last year -- a toxic mix of soot, diesel exhaust, chemicals, metals and aerosols that contribute to heart attack, stroke and lung disease, according to the American Lung Assn.'s annual State of the Air report.
The San Joaquin Valley city displaced Los Angeles, which fell to the third spot in the category of year-round particle pollution, behind second-place Pittsburgh-New Castle, Pa.

