Depends upon how I look at it.
Just as a one-episode issue: nice idea for a story. I like the idea that there isn't an immediate tech fix for everything
. However you can't tell a story like this without it having repercussions on later eps or series. Indeed, that was ignored very quickly, with a throwaway line here or there at best. I also got the feeling that it had been resolved by the moving nacelles of voyager. Both alternatives are ridiculous -- generally a solution to such a fundamental problem that has been overlooked for centuries won't arrive within a year. So either don't tell the story at all or take the consequences seriously (thereby possibly handicapping your own storytelling potential).
As a metaphor for polution and current environmental issues: meh, cheap.