Asbestos-related disease

Hierarchy of Control

​The hierarchy of control measures orders the most effective ways to control risks at the top to the least effective at the bottom:

1. ​Eliminating the risk (removing/substituting the asbestos)
2. Isolating the risk or applying engineering controls (for example, enclosing, encapsulation, sealing)
3. Using administrative controls (for example, safe work procedures, using appropriate tools and training)
4. Using personal protective equipment (respirators, disposable gloves, goggles, coveralls)

The ACMs rated the highest risk of releasing fibres should be eliminated from the workplace by professional removal as soon as possible.

​Eliminating the risk – Removing asbestos

​Even where asbestos is contained or in good condition, there is always a risk of fiber release until the ACMs are removed and disposed of by burial in a landfill.

​Asbestos must be removed and disposed of by qualified and trained professionals and in accordance with all workplace laws.

​Managing asbestos in place – isolation and engineering controls

​Where it is not reasonable for asbestos be removed, it must be managed to minimize the risk of asbestos fibres being released. Using the hierarchy of controls, this may be done through a combination of the remaining control options – isolation/engineering, administrative and personal protective equipment controls.

Isolating the risk – Enclosing, encapsulating, or sealing asbestos

​Where it is not reasonably practicable to remove non-friable asbestos that is in good, fair, or medium condition, the preferred alternative control measure is enclosure.

What is enclosure?

​Enclosure involves building a solid structure (such as using plywood) around the asbestos to protect it from damage and inadvertent access. The structure needs to:

• ​allow regular inspection of the ACM’s condition
• prevent impact to the ACM – e.g., an enclosure of an asbestos cement wall in a warehouse may also require protective bollards to prevent accidental forklift impact of both the enclosure and ACM.

If the asbestos cannot be removed or enclosed, encapsulation or sealing will be the next appropriate control measure.

What is encapsulation?

​Encapsulation means binding asbestos in a resilient compound to minimize the release of fibres. Examples of encapsulant compounds include reinforced plastics, vinyls, resins, mastics, bitumen, flexible plasters and cements. Encapsulation will bind loose fibers into place and should be used only when the original asbestos bond is still intact.

Encapsulation helps protect the asbestos from mechanical damage and can be used as an interim measure to extend the life of an asbestos product until it can be safely removed. Encapsulation can also be used to strengthen asbestos materials during removal.

What is sealing?

​Sealing is the process of covering the surface of the material with a protective coating. This only covers the material to minimize asbestos fibre release. This is opposed to encapsulation where the compound binds the asbestos fibres within the compound.

​Speak to suppliers and experts to select a suitable coating for the material and its use. The coating (sealant) may deteriorate if it is exposed to chemicals, extreme heat or cold, wet or dry conditions or physical impacts. The ACM’s location may require the sealant to provide fire resistance, thermal insulation or ultraviolet (UV) protection.

Choosing a different coloured sealant to the underlying asbestos can ensure complete coverage during application and assist with monitoring its condition over time.

​The surface on which the sealant is to be applied should be cleaned first with:

• ​a low-pressure hose and then left to dry
• a HEPA filtered H-Class industrial vacuum cleaner (not an ordinary house-hold vacuum-cleaner) or
• a wet disposable cloth

These actions capture any loose dust or debris from the surface and ensure good adhesion of the sealant. Do not use sandpaper to prepare the surface.

​Apply the sealant using an airless sprayer at low pressure. Several coatings may be needed for full protection. Rollers and brushes should not be used because they cause abrasion or damage to unsealed asbestos and result in fibers being released.

Administrative controls

​These controls help employees and contractors know where asbestos is, what to do to prevent fiber release and what to do in an emergency. Administrative controls include asbestos registers, signs, training, emergency procedures and safe work instructions. Examples include:

• ​guidance on what tools should be used on or near ACMs
• signage not to use power tools on or near the asbestos
• procedures for operating machinery near ACMs

Personal protective equipment

​The provision of personal protective equipment (PPE) is the last line of defense to protect workers if fibres are released by the work they are doing. PPE relies on workers wearing it correctly and is only effective if it fits properly and is used according to the manufacturer’s instructions.​