The biggest problem in the early days wasn't the smell but the ash raining down all over a 1-mile radius around the plant. I remember stories about people having to wash their cars every day because of the ash.
When I lived there in the early 2000s the ash was no longer an issue but the smell was still a problem.
The downtown area was a lot busier, and had very few vacancies, when I was a kid in the '80s. I remember my mom taking me there to buy shoes, get a haircut, and go to the doctor. It seemed very busy then; cars and people everywhere. By the time I moved there in 2000, it was much more desolate, which many people attributed to the plant.
I still wonder if MERC might still be operating today if they had sited it in the industrial park. Even if they didn't use rail, the close proximity to I-95 would've meant much less wear and tear on the downtown streets.
Thank you all for indulging my off-topic curiosity.