I've opened up the ceiling in the addition to my house that was built in the 1970's or 80's. It is right under the roof and it contains insulation which looks like very old fiberglass insulation - that nasty allergenic stuff between to sheets of paper. It's old and disgusting, but my concern is - could it be asbestos? Was asbestos ever used in this way? (I know that it was used for insulating pipes but was it also used for insulating walls and ceilings in this way?