What is Asbestos?
Asbestos was extensively mined around the world, with South Africa leading the production of asbestos in the mid to late 1900s. By the 1970s, South Africa was one of the largest producers of asbestos, operating a thriving export trade with over 10 million tons of asbestos being mined in the country between 1910 and 2002.
Asbestos minerals are divided into two categories: Serpentine Asbestos which has long pliable curly fibres and Amphibole Asbestos composed of brittle, rod- or needle-shaped fibres.
Once extracted from the earth, asbestos-containing rock is crushed, ground and graded. This produces long, thread-like fibres. What actually appears as a fibre is an agglomeration of hundreds of thousands of fibres, each of which can be divided further into millions of microscopic “Fibrils”. These microscopic fibrils easily become airborne and have been well documented to cause serious respiratory diseases leading to fatalities.
White Asbestos – Chrysotile
White Asbestos is part of the Serpentine group of asbestos and only includes one mineral – Chrysotile. It was the most commercially used form of asbestos. Its flexible nature easily allowed it to be used in products and was often combined with other elements such as cement and plastic. It has many desirable properties, which include sound absorption, resistance to heat, fire, electricity and corrosive chemicals.
Brown Asbestos – Amosite
Brown Asbestos or Amosite which is a part of the Amphibole group of asbestos and is composed of brittle, rod- or needle-shaped fibres. Because of these properties, amphibole fibres are more hazardous than serpentine fibres when inhaled or ingested. Brown asbestos was used most frequently in cement sheets and pipe insulation. It can also be found in insulating board, ceiling tiles and thermal insulation products.
Blue Asbestos – Crocidolite
Blue asbestos with its needle-like fibres is also part of the Amphibole asbestos group and was most commonly used to insulate steam engines. It was also used in some spray-on coatings, pipe insulation, plastics and cement products.
Crocidolite – blue asbestos was commonly used to insulate steam engines, and it was also used in some spray-on coatings, pipe insulation, plastics and cement products.
Friable vs non-friable asbestos
Asbestos-containing materials fall into two broad categories: non-friable and friable.
‘Friable’ is used to refer to asbestos-containing materials that can be easily reduced to powder by hand, when dry. These materials are more likely to release measurable levels of asbestos into the airborne environment when disturbed, and generally pose a greater risk to health. Examples of friable asbestos-containing materials include:
- sprayed asbestos fire retardants
- thermal lagging, such as pipe insulation
- low density boards
- sheet vinyl underlay or backing
‘Non-friable’, or bonded asbestos is used to refer to asbestos-containing materials in which the asbestos is firmly bound in the matrix of the material. These materials are unlikely to release measurable levels of asbestos fibre into the airborne environment if they are left undisturbed. Therefore, they generally pose a lower risk to health. Examples of bonded asbestos-containing materials include:
- asbestos cement products (flat and corrugated sheeting used in walls, ceilings and roofs, moulded items such as downpipes)
- vinyl floor tiles (however removal of the glue can be classed as friable)