[zorkus]

My $.02 and anecdotal info: As a resident for ~12 years, my own experience is that in the East End (lived in that area for ~9 years) this specific smell is prominent at certain times. Not always, but there are nights/days when it is very strong, usually starting in the very early morning hours. There are certain weather patterns that seem to facilitate this. And yes, (as far as I know) it is most likely emissions from the Clairton plant. It is quite a bit different where I live now, which is south of Pittsburgh proper, and I am not noticing this specific smell. There are interesting weather patterns throughout this river valley area that seem to layer and maintain that polluted air over specific areas of the city.