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Vermiculite insulation that comes from a particular mine before 1990 is likely to contain asbestos. This is particularly true in the U.S. However, not all types of vermiculite insulation contain asbestos. Since you can't detect the presence of asbestos without special equipment, it's best to assume that the insulation contains the dangerous mineral and to either leave it alone or hire a professional to handle it.

Asbestos was commonly used in cloth wiring, but not all types of cloth wiring contain it. The age, condition, and appearance of the wiring can provide clues as to whether asbestos is present or not, but the only way to know for sure if the wiring has asbestos is to have it tested.

Whether or not to buy a home containing asbestos is ultimately a decision for the homebuyer, and there are several things to consider. When in good condition and contained, asbestos is unlikely to present a health risk—it’s when those tiny fibers are loose and airborne that they become a problem. Consider any renovations you plan on doing to the home that could disturb existing asbestos and the cost of removal. If an inspection finds asbestos in a home on the market, you could negotiate with the seller for a lower price, though this isn’t a sure thing.

Knob and tube wiring is an older type of electrical wiring that's no longer used and generally not considered safe. However, some homes still have it, or may have a knob and tube wiring system that was incorrectly modified or rigged to work with a modern electrical system. Knob and tube wiring may contain asbestos insulation, but the only way to know is to have the material professionally tested.