10.2 Asbestos

Asbestos is a group of fibrous minerals that was widely used in building materials because it resists fire and heat and is strong. Its fibres are tightly bound in most products and are released only when the material is damaged, for example by drilling, grinding, cutting or sanding. Asbestos in weathered roofing shingles and siding can also release fibres as it deteriorates.

Health effects

The risk of asbestos disease increases a great deal when the lungs cannot remove or control fibres that enter them. Three factors decide the likelihood: smoking, the amount and length of exposure, and age.

• Asbestosis is severe scarring of the lungs that reduces their elasticity and makes breathing very difficult. It follows long exposure and can cause disability or death.
• Mesothelioma is a cancer of the lining of the chest or abdomen. It is almost always fatal, can follow a fairly short exposure and has a latency of 30 to 40 years.
• Lung cancer follows long exposure, and the risk is much higher in a smoker. Its latency is at least 30 years.

Work categories

Asbestos work is grouped by risk, and each level needs more controls.

Low risk. Work that does not disturb the material, such as working near asbestos containing material that is in good condition without disturbing it, or moving material that is in clean, sealed bags. Workers must be told about the hazards and trained, and the employer must identify and label areas that contain asbestos.

Moderate risk. Work that needs specific procedures:

• Put enclosures or barricades around the work area, and signs to keep unauthorised people out.
• Workers wear suitable protective equipment and clothing.
• Examples: cutting, drilling, grinding or shaping non-friable products with hard tools, laboratory sampling, taking apart drywall with asbestos joint compound, removing vinyl asbestos floor covering without creating friable waste, taking down an enclosure after removal, and removing pipe insulation that is in good condition with glove bags.

High risk. Work that needs special measures: isolating the work area, decontaminating workers, controlling airborne fibres, disposing of waste and sampling. Examples are maintaining or removing air handling equipment where sprayed asbestos fireproofing is present, repairing, dismantling or demolishing structures with asbestos insulation, and any work that can release large amounts of friable fibre.

Protection and disposal

• Everyone doing asbestos work wears suitable protection and an air purifying or atmosphere supplying respirator.
• Protective clothing must not let fibres through and must cover the whole body from head to toe.
• Put all waste in leak proof containers while still inside the enclosed area, seal and label them, and wipe the outside with damp wipes before the containers leave the storage or waste transfer room.

A study aid, not published or endorsed by IOSH or OSHA. Laws and limits differ between countries.