I used to live in a 2nd floor unit in an apartment built in 1950. There was a golf sized "sink hole" on the floor and I wonder if I may have been exposed to asbestos.
I remember the floor being a hard surface (not hardwood), it was dark/reddish color, might even be glossy. I don't remember it being tiled either since tiles usually have seams and I don't recall any seams. It was more of an uniform appearance. I really wonder it it's made out of. Could it be just concrete?
I remember inside the sink hole there is a rough concrete-like texture, but it had the same dark color as the surface. I don't think it's gypcrete since those weren't available in 1950.
It's been a long time but I'm a bit concerned now that I think of it. On the bright side, we didn't disturb it much though (aside from occasional wet mopping), plus the fact that the damage is on the floor means gravity is on our side (hopefully). We lived there for a year.