Despite continuing air-quality improvements, Lancaster was the 10th-smoggiest midsize metropolitan area in the United States during 2010, according to a report.
Using data from government air-quality monitors, the Philadelphia-based group PennEnvironment also found the Lancaster area tied with Pittsburgh for the second-most number of unhealthy smog days among all metropolitan areas in Pennsylvania.
Philadelphia had the worst smog in the state, according to the report, “Danger in the Air: Unhealthy Air Days in 2010 and 2011.”