I am not a doctor, I just find steel interesting. I also prefer leaf to hash. but I think it’s going to take more than 1000C to create the fumes osha is mainly concerned about, which would make the steel yellow with heat, Even for welders it’s the sort of thing that should concern only people who do it professionally. That said you are kinda directly huffing whatever is coming off it (hypothetically of course). If it’s getting red hot, then it might still be having some oxidation, but it probably isn’t getting into your lungs and it probably is going to stay put in the metal, Probably…

If it’s not glowing at all you are definitely good.

Chromium is only dangerous (in reasonable quantities) when its Hexavalent (meaning it has 6 missing electrons). Trivalent chromium (3 missing electrons) is actually essential in trace amounts. Stainless steel has trivalent chromium. Exposure to high temperatures (welding, plasma cutting, maybe grinding) can oxidize it from trivalent to hexavalent but your kitchen utensils aren’t going to be exposed to that. I’m not an expert though to be clear.

Are you looking for something like Lidarr?

the top stairs could have been added later, why demolish the old stairs if you don’t have to.