More often poor people moved near industry because the land was much cheaper on account of it being less desirable. There are some high-profile modern examples where industry moved into existing communities, but that's historically atypical.
Of course by the 3rd of 4th generation it becomes a distinction without a difference. But understanding patterns of development is important. If today you want to prevent poor people from tomorrow living in polluted areas, rich people have to make it easier to build affordably in nicer areas--e.g. allow increasingly dense development so poor people don't get pushed toward industry.
This isn't true for the town Elon moved into in TX to house his new xAI datacenter. It was an existing town and they are using portable generators that are completely destroying the air in the town. All happened in the last 2-3 years. And because the generators are "temporary" they didn't think they needed EPA approval. They are apparently breaking existing laws, and told the community only a few of the generators were online, however infrared photography showed that almost all of them were operational.
Of course by the 3rd of 4th generation it becomes a distinction without a difference. But understanding patterns of development is important. If today you want to prevent poor people from tomorrow living in polluted areas, rich people have to make it easier to build affordably in nicer areas--e.g. allow increasingly dense development so poor people don't get pushed toward industry.