Don't forget coal fired heating, and the air prior to clean air legislation. Smogs were a common occurrence and included industrial and coal smoke. Much like is seen in China and India today.
Smogs were not just of Victorian London. :)
Yes. Yes. And decades of accumulated grime.
GCT has never had a coal fired train in it - its always been an electric only station, Penn is the same.
While that's true, it was only until 2003 smoking was banned completely from GCT.