I think I myself had inadvertently exposed to asbestos. What happened that I wanted to put some limits in brackets, a small hole in the ceiling drilling required. To make sure I do not always near a power line for reference, I went into the unfinished attic. After removing the small cover that gives access to the room, I discovered a way to soft dark gray insulation was blown in insulation in fiberglass. At this point I walk back and will not crawl in the attic, but this sort of thing (it could be wool, but not sure) was thecover so I know I am certainly happy with him. If it helps, my house was built from 1968 to 1974. I told some people about this, and they tell me they are well aware that asbestos in bulk was used. “What did you think of this or know how?