What is Asbestos?

The term "asbestos" describes six naturally occuring fibrous minerals found in certain types of rock formations. It is a mineral compound of silicon, oxygen, hydrogen, and various metal cations. Of the six types, the minerals chrysotile, amosite, and crocidolite have been most commonly used in building products. When mined and processed, asbestos is typically separated into very thin fibers. When these fibers are present in the air, they are normally invisible to the naked eye. Asbestos fibers are commonly mixed during processing with a material which binds them together so that they can be used in many different products. Because these fibers are so small and light, they may remain in the air for many hours if they are released from the asbestos containing material (ACM) in a building.

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Asbestos in Public and Commercial Buildings

As a building material additive to enhance strength (for example, asbestos was added to concrete, asphalt, and vinyl materials in roof shingles, pipes, siding, wall board, floor tiles, joint compounds, and adhesives)

• As a fireproofing material applied on steel beams and columns during construction of multistory homes
• As a thermal insulation and as a means of controlling condensation
• As an ingredient in acoustical plaster
• As a component of a mixture of sprayed on ceilings and walls to produce a soft, textured appearance.

If the materials discussed above contain more than one percent asbestos, they are considered asbestos-containing materials (ACM). ACM can be friable or nonfriable. When dry, friable ACM can be crumbled or reduced to a powder by hand pressure and presents a greater risk to human health than nonfriable ACM. When dry, nonfriable ACM cannot be crumbled or reduced to a powder by hand pressure.

How is asbestos used?

Asbestos is widely used throughout the world, particularly in building and insulation materials. Typical uses include:

Boilers and heating vessels

Cement pipe

Clutch, brake, and transmission components

Conduits for electrical wire

Pipe covering

Roofing products

Duct and home insulation

Fire protection panels

Furnace insulating pads

Pipe or boiler insulation

Sheet vinyl or floor tiles

Underlay for sheet flooring.

Why is asbestos a problem?

Damage to asbestos-containing material can result in the release of small asbestos fibres that become airborne and are readily inhaled. These fibres can remain in the lungs for long periods and can cause serious lung disease.

What are the health concerns?

The principal health concerns are the development of asbestosis, lung cancer, pleural thickening and mesothelioma. These diseases have long latency periods, in the order of 10-50 years.

Asbestosis:Thisis a slowly developing and progressive scarring of the lungs caused by the inhalation of high concentrations of asbestos dust and/or long exposure. The elasticity of the lungs is reduced and also their ability to exchange gases. The result is decreased lung volume, increased resistance in the airways and reduced oxygenation of blood. It is associated with occupational rather than environmental exposure. Advanced asbestosis is often associated with lung cancer, especially among smokers.

Lung cancer The risk is related to the nature of the occupational exposure and also to smoking: smokers have a higher risk of developing lung cancer than non-smokers when exposed to asbestos.

Diffuse pleural thickening This is a non-malignant disease in which the lining of the lung (pleura) becomes scarred. Small areas of scarring are called pleural plaques. The disease is a chronic condition with no cure.

Mesothelioma This is a malignant tumour of the pleura or peritoneum. It is linked with exposure to all types of asbestos. As well as being an occupational hazard, it may develop in non-occupationally exposed people living in the same household as asbestos workers or in the vicinity of strong asbestos emission sources.

What is a safe level of exposure?

Asbestos is a proven human carcinogen (IARC Group 1). No safe level can be proposed for asbestos because a threshold is not known to exist ¹. The greater the exposure, the greater the risk of developing lung disease, therefore exposure should be kept as low as possible. A number of occupational exposure limits have been set:
The USA Occupational Safety and Health Administration (OSHA) standard for asbestos in the workplace is² 0.1 fibres/ml of air as an 8-hour Time Weighted Average.