My wife and I moved into a 1962 home in the Boston suburbs a couple of years ago. The finished basement had ratty old carpet, which we replaced, and in the process became pretty sure that underneath it were 9x9 asbestos vinyl tiles. We decided they were fine where they were, and didn't disturb them at all.

Our furnace room is just off the finished basement, and had what looked like a painted concrete floor. We recently got some water in that room and arranged to add an under-floor drainage system, but after the trench had been dug and jackhammered out, I realized that the same floor tile was underneath the top layer and several tiles were broken.

I understand from reading several posts on this forum and elsewhere that floor tiles are very low risk even when cracked - is this backed up by any actual studies anywhere? I'm trying to decide how worried to be, especially as our basement is the playroom for our one year old. It'll be a week or so before the room is fully usable again; should I keep him out of there for longer, or should I not worry about what's likely a minimal or non-existent exposure?