What is asbestos?
Asbestos is a naturally occurring fibrous material which has been regularly used from the end of the 19th century until the late 1990s in both manufacturing and construction.
Thanks to its versatile properties, such as its fire-resistance and the fact that it is the only known mineral that can be woven into a thread, it had been known as the ‘magic-mineral’.
Asbestos has been found to be a hazardous substance and needs to be handled with care. When asbestos is disturbed it releases fibres as well as a visible dust which can present serious health risks when breathed in. It can be fatal.
Types of asbestos
There are 6 mineral types that are defined by the Environmental Protection Agency as ‘asbestos’, and these are split into 2 main classes of asbestos.
Serpentine – Serpentine class fibres are curly in appearance. There is only one member in this class of asbestos, called Chrysotile.
- Chrysotile asbestos is obtained from serpentinite rocks, which are found commonly throughout the world. Chrysotile appears under the microscope as a white fibre. This type of asbestos has been used more than any other, as it is more flexible than any of the Amphibole class asbestos and can be spun and woven into a fabric. Its most common use has been in corrugated asbestos cement roof sheets typically used for outbuildings, warehouses and garages. It may also be found in sheets or panels used for ceilings and sometimes for walls and floors. Chrysotile has been a component in joint compounds and some wall plaster. Numerous other items have been made containing chrysotile, including brake linings, fire barriers in fuse boxes, pipe insulation, floor tiles, and gaskets for high temperature equipment.
Amphibole – Amphibole class fibres are needle-like in form. The remaining 5 types of asbestos fall into this category, including Crocidolite, Amosite, Tremosite, Anthophyllite and Actinolite.
- Crocidolite asbestos is the fibrous form of the amphibole riebeckite. Crocidolite is seen under the microscope as a blue fibre. Often referred to as blue asbestos, it is considered the most hazardous. In 1964, Dr Christopher Wagner discovered an association between blue asbestos and the asbestos related cancer mesothelioma. Unbelievably, Bolivian-mined crocidolite was used in Kent Micronite cigarette filters in the 1950s. Blue asbestos was also formerly used in early gas masks.
- Amosite asbestos, often referred to as brown asbestos, is seen under a microscope as a grey-white fibre. It is found most frequently in materials used as fire retardants in thermal insulation products, asbestos insulation and ceiling tiles.
- Tremolite, Anthophyllite and Actinolite asbestos are used less commonly industrially, but can still be found in a variety of construction and insulation materials, and have even been reported to be found in a number of consumer products in the past.