I live in a home built in 1930. The only insulation in the attic is 2 inches of Rockwool; put in around the same time. Rather than remove it completely, I have been shifting it around to areas where the joists are only a few inches from each other (width of 2 to 4 inches). In the cleaned out areas, I have been installing fiberglass batts.
Here is my question --- does this stuff contain asbestos or is it very harmful to breath in? I have a mask on, but it is one of those $4 fiberglass masks from HD. Should I be taking more precautions?