Asbestos is said to describe a group of naturally occurring fibrous mineral silicates. It is not uncommon to find asbestos in structures built between the 1950's and the late 1980's. Asbestos was used as insulation, fire protection or added to cement and plaster materials to increase structural strength. Fine, light asbestos fibres may remain suspended in the air for long periods of time if disturbed. There is little risk of fibre release if asbestos-containing materials are in good condition and not disturbed. However, asbestos becomes a hazard if it is in poor condition, handled, sanded, drilled, broken up or crumbled. This causes the release of fine, light asbestos-contaminated air poses serious long term health effects, such as lung disease and cancer.