This is…factually incorrect, and honestly insulting.

No I mean actual measurable particulate counts in the air around factories, and the industrial vehicles moving goods in and out of those factories. When people talk about “environmental racism”, that is: making poor people live in the worst parts of town, they’re talking about the environmental aspects of those parts of town.

They left as soon as it became practical to leave (introduction of cars and suburbs) because of crime. The crime rate back then was inconceivable to anybody living in America today.