There are two groups, and six common types:
|Serpentine Group||Amphibole Group|
|Chrysotile (White)||Amosite (Brown)|
White asbestos was the most common form of asbestos used in New Zealand, followed by brown asbestos; and blue to a lesser extent.
White asbestos has long, curly fibres not unlike cotton wool, used primarily for its strength and flexibility. Its versatility made it the most common type of asbestos in building and household products.
Brown asbestos has harsh spiky fibres, used mainly for its fire resistant and thermal insulation properties, in insulation board, ceiling tiles, asbestos cement sheet and pipe insulation. The brown asbestos used in insulation board and ceiling tiles is likely to be a compressed asbestos product with the potential to release air borne fibres if damaged during normal occupation, or during repair or replacement work.
Blue asbestos has straight thin needle like blue fibres, used mainly for its fire protection and thermal insulation properties and often used as a sprayed coating for structural fire protection, pipe insulation and in cement products. Blue asbestos is claimed to be the “most dangerous asbestos” because of the nature of the fibres, which make them easy to inhale and lodge in a person’s lungs. However all types of asbestos should be treated with equal caution, as all types of asbestos fibres can be inhaled into the lungs.
Asbestos use in New Zealand
Materials containing asbestos were widely used in building construction in New Zealand from the 1930s until the mid-1980s. Peak production and use of ACMs in New Zealand occurred in 1975. Production of ACMs continued into the 1980s, as manufacturers used up their stock following a ban on the import of raw asbestos from 1984.
Health effects of exposure to New Zealand
It’s estimated that around 170 people die from asbestos related diseases annually in New Zealand, which makes asbestos exposure the single biggest cause of work-related death. Breathing air borne fibres may cause diseases like asbestosis, lung cancer and mesothelioma.
Most asbestos related diseases have a long latency period and take around 20 years for symptoms to develop.
Friable and non-friable asbestos
Asbestos falls into two categories, friable and non-friable.
Friable: asbestos that’s in a powder form or able to be crumbled, pulverised, or reduced to a powder by hand pressure when dry. While all asbestos has the potential to become airborne, friable is more likely to become airborne.
Non-friable: asbestos that’s not in a powder or cannot be crumbled, pulverised, or reduced to a powder by hand pressure when dry. It is usually in a bonded form, such as asbestos cement sheet in good condition.
Although bonded asbestos products (including asbestos cement water pipes, wall and roof cladding and rainwater goods) are normally considered non-friable, the material may become friable with the potential to release air borne fibres as a result of weathering or damage. Some asbestos cement products manufactured in New Zealand contain Brown and Blue asbestos which are more susceptible to weathering than white asbestos and break away from the cement matrix potentially releasing airborne fibres.