The impression this is giving to me is that your father can't win this.
Erik says we can't read their minds and seems to be implying that we can't say much about the issue, but from your description and my experience in several companies a couple of things seems quite sure to me and they clearly lead me to the conclusion that there isn't much hope.
The factory your father works in spent a lot of money on this new system. Most certainly several people were involved in the decision, because if one person were responsible, he'd already be taking care of it. If things like these go seriously wrong with nobody clearly responsible, nobody wants to take responsibility, and everyone is hoping someone else will do it. The first one to do anything about it will probably be the one who's blamed for the whole thing with no exception, so there is simply nobody who wants to give the slightest bit of impression of accepting even the slightest bit of responsibility for any bit of the whole mess although someone taking care of it would be in the best interest of the company. But the dynamics of the whole thing make sure there's no one.
This in turn leads to the situation that the manufacturer or the company that sold and installed the system won't be made liable, which in turn means that if anything should be done about the mess, they'd charge extra. Which in turn is turning into an additional obstacle. Your father's company already wasted a lot of money, and now they should spend even more? With everything being said, who should be the one to sign this?
It seems that his managers seem to have abandoned the idea or plan of eventually proving this to be a good investment in any way, i.e. getting the problems fixed and getting the system make their production more efficient than it was before, even if it requires a few more bucks they'd have to spend. We can only speculate about the reasons (maybe a long legal dispute with the manufacturer, or totally exploding costs beyond what can ever be returned), but they don't actually matter. The result is always the same: Nobody will do anything.
Another possibility is that buying this stuff was even some kind of friendly turn of a manager, or some other kind of corruption was involved. Everybody was hoping it would go through, everybody would be happy in the end, so nobody would notice anything, but then it all went wrong. Which would also be a strong reason to assume that everybody involved is currently keeping their heads low, hoping the issue will just settle, production will go on, they will be out of the line of fire until some miracle happens.
Bottom line is always the same: People who could do something about it don't want to see or even concede and solve any of the problems, they rather want as little fuss as possible. Even though it may be against the interest of the company, individual thinking lead to this behavior.
I can't make any other sense of what you're describing.
Given I'm right your father has only a few options: Either he starts a HUGE fuss that they can't ignore anymore, but I don't think it would improve his situation much. I still think the last thing any of them would do is take responsibility. They'd rather sacrifice your father (even though this may be more difficult than it sounds because he may be the only one having the essential know-how). Or he accepts the situation as is, which sounds like not the best thing to do with regard to his health. If he reports the company to authorities, they may shut the whole thing down, at least for a while, and he will not get happy there anymore either. If he resigns without doing anything about the issue in particular, he'll have his peace but put new applicants at risk.
Unless there's some joker like for instance having the company owner's phone number because they once went fishing together or anything of that kind I don't see much he can do.
The only remaining option is making own arrangements with the situation. Getting a gas mask (from his own money if nobody from the company is helping), finding a working style that doesn't put him in danger. Keeping things up as usual, that is giving his managers what they're hoping for although this isn't what they're really entitled for.
He may, however, have a better chance than ever to negotiate a substantial pay rise. In case they really want to avoid a fuss about everything, they will realize they need him.
If he chooses to go that way, he should just make double sure he can prove that he did report the problems long ago. Just in the unlikely event that things go seriously wrong and he's blamed for anything of the mess at any point, he should be able to prove he notified them several times and very clearly, and they just didn't care.
Disclaimer: Strictly speaking I'm only guessing what's going on behind the scenes there. I may be totally wrong. Only take it as a starting point for your own thoughts.