This insulation product was sold as rigid slabs that were usually made with fiberglass, recycled rag, agricultural filler and a range of other materials. One such material was asbestos, as it had the properties required to make the block insulation resist longer to extreme heat.
Block insulation subjected the workers to asbestos exposure when they had to disturb the asbestos fibers, as they were cutting the blocks for fit or breaking them apart in order to remove them. In the process, asbestos dust would have been spread in their environment. You could have been exposed if: