Asbestos is a tiny fiber that was used in the past primarily as insulation. It was also added to some building materials to provide added strength and flame resistance.
The problem with asbestos is that it has been shown to cause lung cancer and mesothelioma in individuals that were exposed to large amounts of free-floating asbestos fibers in the air.
These conditions typically did not become apparent until around 30 years after the exposure. Because of the health hazards of asbestos fibers, its use in insulation and paint was banned in the 1970’s.