Asbestos is a mineral found in rock – a compound metallic silicate that occurs naturally.
There are three main types of asbestos;
In Australia, all of the asbestos types were used in various applications up until the late 1960s.White, and some brown, asbestos usage continued until the early 1980s, including in building products.
There are two classes of asbestos types.
Friable (Class A) Asbestos is classified as any material found under ground level, as well as a few older forms of insulation used in domestic heaters and stoves and in ceiling insulations products. Ceiling insulation containing asbestos was generally used in commercial buildings. In most cases, glass fibres have replaced asbestos in today’s insulations products.
Non-friable (Class B) Asbestos is a fibre-cement product. The asbestos in firmly embedded in a hardened matrix. The bonded sheets are flat, corrugated or circular tubes.
Biological Properties of Asbestos Fibres:
- Fibre length 5-100 micrometres
- Coarse and longer fibres deposited in larger airways
- Fine fibres enter lung tissue where they cause intense tissue reaction
- Crocidolite fibres shorter and stiffer; split into straight fibrils; Amosite also fragments
- Chrysotile fibres are longer flexible fibres