If your home was built between 1930 and 1950, there is a possibility that it has asbestos insulation. Asbestos is a major health risk, and if you suspect you have this in your home, you should contact a professional as soon as possible.

The fibers from asbestos can cause lung cancer and mesothelioma. Never try to remove material you suspect to be asbestos by yourself, even if you think you are taking precautions. If left undisturbed, it shouldn’t pose a danger, but if the fibers become airborne they can easily be inhaled.

Asbestos is a natural fiber, so if the insulation in your attic looks somewhat like gray wool, it might be asbestos. There is also a type of insulation called vermiculite, which looks like small, grayish pebbles with some metal streaks. Vermiculite contains asbestos and should be removed.
Never try to remove asbestos yourself, and do not hire someone to do it that doesn’t have the experience. If improperly handled, a trail of fibers can be left in your home.