Seems you have real crappy source where a lot of stupid global search and replaces have been made. "tillmakningen" should be "tillgången", i.e. access. (I suspect a S/R on "gång", which as a word all by itself in a mining context would mean "gallery" or "drift", but how that becomes "makning" is beyond me, or it is just "gå" that's been substituted with "makni", but that's just as puzzling.)
As for the osdagar, well "os" does mean "odours", or probably more fitting in this context, "fumes". I can't figure out that it would mean anything but simply periods with very much fumes. But I'm guessing.
Another possibility would be that it is simply a misspelling and should be "onsdagar", i.e. "Wednesdays", but why access would be restricted to a specific day of the week beats me.