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11.1.4 Airborne Asbestos Fibres
The physical structure of asbestos enables it to break up into small fibres, which are capable of remaining suspended in the air for long periods. These
fibres may be inhaled and some may penetrate to, and be deposited in, the lungs.
A „countable‟ fibre is defined as a particle having a length: breadth ratio of
greater than 3:1, being less than 3 microns in diameter and greater than 5 microns in length.
11.1.5 Exposure to Asbestos Fibres
Asbestos fibres asbestos dust may be emitted into the workplace environment during the manufacture, use, machining cutting, drilling, etc.,
removal and disposal of asbestos-containing materials or products, and due to deterioration in the condition of asbestos containing materials in-situ. Building
maintenance workers plumbers, electricians, etc. are thought to be particularly at risk as a consequence of the extensive use of asbestos in older
buildings. The eventual removal of the remaining asbestos stock from buildings will be a major challenge. Examples of some typical exposures are
given below:
Activity fml
Dry removal of lagging Up to 100
Drilling of asbestos insulation board
Up to 10
Hand sawing of asbestos insulation board
Up to 10
Drilling of asbestos cement Up to 1
Hand sawing of asbestos cement Up to 1
Use of a circular saw Up to 20
11.2 Health Hazards of Asbestos
Inhalation of respirable asbestos fibres may give rise to a number of serious diseases.
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Asbestosis: Prolonged exposure to airborne asbestos fibres at levels in
excess of the Hygiene Standards may lead to local thickening of the lining of the chest pleural plaques and to the formation of fibrotic scar tissue in the
deep lung, resulting in the progressive reduction in elasticity of lung tissue, impairment of respiratory function, and reduced life expectancy
Cancer of the Bronchus and Lung: Asbestos workers have been shown to
suffer an increased risk of bronchial and lung cancer. Cigarette smoking can also cause these cancers and it has been shown that cigarette smokers
exposed to airborne asbestos fibres are at a significantly greater risk of developing cancer than similarly exposed non-smokers A synergistic effect.
Mesothelioma: Exposure to asbestos, particularly crocidolite and amosite,
can result in the development of mesothelioma, an uncommon and usually incurable cancer of the pleura the lining of the chest wall and lung or more
rarely the peritoneum the lining of the abdominal cavity. Mesothelioma may develop 20 or more years after a brief period of exposure.
11.3 Asbestos Register 11.3.1 Function of the Asbestos Register
The function of the Asbestos Register is to record the usepresence of all asbestos and asbestos-containing materials at work sites. In areas where
asbestos has been used extensively in the past, it may be necessary to develop the Register over a period of time. In the interim, it may be advisable
to assume that certain insulation and building materials contain asbestos and, until their identity is established, the appropriate precautions taken. Register
information can be used to: record the location of all asbestos materials on site.
ensure that the condition of asbestos-containing materials are
frequently inspected and any necessary remedial action is instigated. ensure that any work with asbestos or asbestos-containing materials is
carried out in an approved manner.
108 minimise the acquisition and use of materials or equipment, which may
contain asbestos.
11.4 Remedial treatment of Asbestos Containing Materials 11.4.1 Asbestos Removal
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