Unflattering Listage: One of the 'Dirtiest'

The Philadelphia-Camden-Wilmington metro area comes in at No. 3 on Forbes' confusingly named list of "America's 20 Dirtiest Cities." Given that the city's nickname has, at times (always?), been Filthadelphia, it wouldn't be surprising if the rankings referred to street trash. But in this case the issue is environmental filth and degradation: "the harsh, lung-searing, rash-inducing reality for millions of people in some of America's biggest cities." Including this one. [Forbes]