Function of the ing-forms in this sentence?

I'm having a hard time figuring out what the exact function of "fascinating" and "working" is in the following sentence:

"This song deals with the most important concerns fascinating people working at a factory."

Do they both introduce a ing-clause or do they function as adjective phrases or something else entirely?

Thanks in advance!

They are both non-finite clauses modifying concerns and people respectively. These are interpreted similarly to relative clauses (CaGEL p1263-1265), approximately:

...the most important concerns that fascinate people who work at a factory

or, depending on the context, they could also be interpreted with a progressive aspect:

... the most important concerns that are fascinating people who are working at a factory