Could very old batt-type insulation contain asbestos–can identify type, could be from the 1920s?
The attic is supposed to be open to the atmosphere, for ventilation. Do nothing that would lower your ventilation area, otherwise you will get moisture damage. Sounds like the batts may be rock wool. Sure, it may contain some asbestos, but so what. It is in the attic, and your ceiling already prevents it from getting dust in your home. Abatement is keeping it in place and preventing it from getting in your house. Nothing to worry about at all– the problem with asbestos is disturbing it and making the dust stir up where it can be inhaled. That doesn’t happen in your attic, and since it is under other insulation, it sure won’t get disturbed. Sleep easy, you are fine. If you look at the hazard ratings, asbestos is actually way down the list. Gasoline you inhale while filling your car is way worse! And silica, plain ole’ sand, is also more dangerous. Long term direct exposure, as many people in industry had years ago, led to lung disease. But it was an easy target and the industry was des
