Notice what three of the five of the photos have in common? They depict cities shrouded in haze.
Then read the story...Philadelphia and New York don't have an air pollution problem, they have a groundwater problem resulting from the dumping of industrial wastes.
So an editor in a hurry probably just typed in 'Philadelphia' and 'pollution' or 'haze' and threw in the ugliest photo that popped up. The photo doesn't outright lie -the city does have some hazy days - but it doesn't tell the story, either.
This is a pet peeve of mine - many web photos are generically chosen from stock or wire services and really don't have much to do with the stories they are attached to. Sometimes they exaggerate the content, sometimes they are just irrelevant. Either way, this is sloppy journalism. Images matter. I hope editors care more than this.