Asbestos is a fibrous inorganic mineral material widely used in building and HVAC insulation and other building materials in the middle of the last century. It was banned in the 1970's and an intensive removal effort has occurred. A material containing asbestos is called friable when the material can be crumbled, pulverised, or reduced to a powder in the hand.
Asbestos causes asbestosis, or fibrosis of the lungs, sometimes leading to cancer. It also causes cancer of the larynx and is suspected of causing cancer of the gastrointestinal tract. It is generally people who have been exposed to high concentrations of asbestos fibres in the air who develop serious health effects from their exposure.
Asbestos is contained in the following materials:
| Product type | Purpose | Generally found |
| Acoustical | Sound control | Ceilings in classrooms, halls, multi-purpose rooms |
| Thermal insulation | Safety-energy conservation | Pipes and boilers |
| Steel fireproofing | Fire protection | Covering structural steel |
| Asbestos cement board | Fire protection | Near furnaces and boilers |
| Tile and sheet flooring | Cleanability-decor | Floors, classrooms and halls |
| Textiles | Fire protection | Auditorium curtains, laboratory aprons and gloves |
Asbestos is generally not considered dangerous unless fibres of asbestos from the material containing the asbestos are released into the air. Dry applied materials are often in the category which can release fibres. In many cases the asbestos is covered with a sealed covering to reduce or eliminate the release of fibres into the air.