Safe management of synthetic mineral fibres (SMF) – glasswool and rockwool

This information guide explains safe management of synthetic mineral fibres (SMF) - specifically, glasswool and rockwool.

Information on the safe use of Refractory ceramic fibres (RCF) can be found in SafeWork Australia’s guide to handling refractory ceramic fibres 2013.

1. Background to SMF

Synthetic mineral fibres (SMF) is a term used to describe a fibrous product manufactured by the process of blowing or spinning a molten mineral raw material into a fibrous ’woollen’ product that is used for insulation.

SMF can be classified into three groups:

  1. Glasswool: is manufactured by melting glass into a fibrous ’wool’
    • used as thermal and acoustic insulation in the manufacturing and construction industry
    • does not include fibreglass used in boatbuilding, surfboards and other industrial applications because they contain catalysts and resins  which require different work practices.
  2. Rockwool: is manufactured by melting volcanic rock (usually basalt) into a fibrous ’wool’
    • also known as slagwool
    • used  as thermal and acoustic insulation in the manufacturing and construction industry.
  3. Refractory ceramic fibres (RCF): are made from kaolin (a naturally occurring alumino-silicate clay or a synthetic mix of alumina) used as:
    • high temperature, high performance thermal insulation, eg: in furnaces, kilns and other industrial heaters
    • insulation in the automotive, marine, petrochemical, steel, aluminium, ceramic, glass and construction industries.

For over 70 years, glasswool and rockwool insulation materials have been the most widely used insulation in Australia.

1.1 SMF classified as possibly cancerous to humans in 1987

Concerns from research into other building materials in the 1970s (eg asbestos) led to questions being raised about possible health effects of SMF products.

In 1987, based on some early research findings the International Agency for Research into Cancer (IARC), an agency of the World Health Organisation (WHO), classified all SMF as ‘Category 2B - possibly carcinogenic to humans'.

1.2 Change to SMF classifications in 2001

Throughout the 1990s, further extensive medical and scientific research was conducted and then reviewed by the IARC in 2001. As a result of this review:

  • Glasswool was reclassified down to 'Category 3 - not classifiable as carcinogenic to humans’,
  • Rockwool was also reclassified down to 'Category 3 - not classifiable as carcinogenic to humans’, but
  • RCF remains classified as ‘Category 2B - possibly carcinogenic to humans' and, therefore, a hazardous substance.

Since 2000 – 2002, all glass and rockwool insulation products manufactured in Australia have been biosoluble, allowing the product to dissolve in bodily fluids and be quickly cleared from the lungs. Despite this, it should be remembered that workers can still be exposed to SMF made of lower quality imported products.

1.3 Health effects from exposure to glasswool and rockwool

Dust from glasswool and rockwool products may cause:

  • discomfort, tickling and dryness of the nose, throat and respiratory tract, especially for those who suffer hay fever, asthma or bronchitis;
  • temporary skin irritation, particularly where there is rubbing from clothing such as cuffs and collars; and
  • severe irritation to eyes.

2. Who has responsibilities?

Manufacturers, importers, suppliers and installers:

Manufacturers, importers, suppliers and installers must ensure, so far as is reasonably practicable, the glasswool and rockwool they manufacture, import, supply or install is without risks to health and safety including:

  • carrying out testing and analysis (manufacturers)
  • providing information to users to enable the safe use of the product
  • manufacturing, importing, supplying or installing glasswool and rockwool materials which emit a minimum amount of fibres and/or dust, especially during transport as well as when being cut and shaped.


PCBUs must ensure, so far as is reasonably practicable, that workers and other people are not exposed to health and safety risks arising from exposure to glasswool and rockwool at airborne concentration levels that exceeds the workplace exposure standards for airborne contaminants (2013).

When working with glasswool and rockwool products, the dust concentrations capable of being inspired can vary greatly depending on the circumstances in which it is being used, eg: work installing new insulation batt products into old ceiling spaces or removing worn and damaged insulation is likely to involve inspirable dust levels that may include dusts other than glasswool and rockwool.

While there can be significant amounts of respirable fibres in all wool insulation products, in most situations, routine air monitoring is not required when it has been clearly established that the work practices outlined in this information guide are being followed.

Routine medical surveillance of workers who work with glasswool and rockwool products is NOT necessary as harmful health effects should NOT occur if exposure to the fibres is kept below the level specified in the workplace exposure standards for airborne contaminants.

The WHS Regulation 2017 prescribes specific duties in relation to workplace exposure standards:

  • Regulation 49 requires PCBUs to ensure that no person at the workplace is exposed to a substance or mixture in an airborne concentration that exceeds the exposure standard for the substance or mixture.
  • Regulation 50 requires PCBUs at a workplace to ensure that atmospheric monitoring is carried out to determine the airborne concentration of a substance or mixture at the workplace to which an exposure standard applies if: ‘the person is not certain on reasonable grounds whether or not the airborne concentration of the substance or mixture at the workplace exceeds the relevant exposure standard, or monitoring is necessary to determine whether there is a risk to health’.

The exposure standards referenced in the WHS Regulation are those published in the workplace exposure standards for airborne contaminants.

To achieve low airborne concentrations of fibres, the PCBU must ensure that:

  • the manner in which glasswool and rockwool products are purchased, handled, stored or disposed of in the workplace minimise the release of fibres and/or dust
  • workers are provided with appropriate instruction, training and information about how to safely use glasswool and rockwool products
  • Safety Data Sheets (SDSs) are obtained and are readily available to workers and their representatives
  • all containers or packages of glasswool and rockwool are clearly and appropriately labelled.


Workers have a duty to take reasonable care for their own and others health and safety and co-operate to make the workplace safe.

This includes following WHS policies and procedures and wearing personal protective equipment (PPE) if provided.

3. Factors that impact the risk of exposure to glasswool and rockwool fibres

There are four main factors which alone, or in combination, determine the fibre levels present when working with glasswool and rockwool and which therefore determine the risks that may arise and how these risks might be managed.

The four factors are the:

  • proportion of respirable fibres in the product
  • degree of disturbance of the product
  • extent of any binders, cladding or sealants, and
  • ventilation in areas where the product is being used.

4. Types of glasswool and rockwool insulation

There are two basic forms of glasswool and rockwool insulation and the procedures to be applied to remove the product depend on the form of the original glasswool or rockwool insulation installed.

  • Bonded insulation contains binding agents (such as adhesives or cements) that have been cured in the manufacturing process prior to packaging and delivery and the products have a specific shape, such as in a batt or blanket form or as compressed boards. Additionally, some bonded materials may be clad in various coverings on one or more sides. The advantage of the presence of binding agents is that they significantly reduce fibre release during handling.

    Typical examples of the use of bonded glasswool and rockwool materials include:
    • preformed insulation batts in ceilings and cavity walls
    • insulation blankets or batts around air conditioning ducts, and
    • preformed pipe sections as lagging around steampipes and hot or chilled water pipes.
  • Unbonded insulation has no adhesives or cements and is loose material packed into a package. This type of material can be packed loose or mixed with adhesives or cements before, or during, installation. There are three  main types of unbonded glasswool and rockwool materials:
    • wet spray: where the fibres are mixed with cement and sprayed as fire protection in multi-storey buildings
    • loose-fill: where the material is sprayed into ceiling and cavity spaces of buildings, and
    • dry spray: where densely packed  material is blown dry into a closed stud cavity.This method should only occur where the target area is enclosed to prevent the release of loose fibres. Typical examples of the use of dry spray include cavity-wall and loose fill in existing construction undergoing an insulation retrofit.

5. Practical solutions to control exposure to glasswool and rockwool insulation products

5.1 General work practices

Action should be taken on a continuing basis to achieve the lowest possible level of airborne fibres and dust, using the hierarchy of controls. In the glasswool and rockwool insulation industry, engineering controls are usually the most effective control measures to implement.

Administrative controls and PPE are the least effective and the least reliable controls and must only be used for any leftover risk that cannot be controlled by a higher level control.

Administrative controls and the use of personal protective clothing and equipment (PPE) rely solely on human behaviour and require constant supervision.

Engineering controls: eg local mechanical exhaust or dilution ventilation to contain or minimise exposure to fibres and dust.

Administrative controls:

  • order materials in a form and shape which requires minimum of cutting and handling on site.
  • develop safe work practices that adhere to product usage information as defined in the SDS, including dust suppressants to reduce the release of dust and fibres.
  • designate specific work areas using barriers for all overhead work involving glasswool and rockwool. Workers not engaged in this work should not be within 3 metres of the work area.
  • install appropriate signs in glasswool and rockwool work areas.

All warning signs should comply with AS 1319:1994 Occupational signs for the work environment.

  • always use manual hand tools in preference to power tools to trim or cut SMF materials. (If power tools are used, they should be fitted with exhaust extraction at the point where the  dust is generated or supply other effective local exhaust ventilation).
  • store packaged or in intact containers or under sheet covers in low traffic areas and transfer from storage to the point of use in sealed containers or bags. Take care when opening boxes or bags to minimise dust release
  • spray or gun glasswool and rockwool materials in a wet, rather than dry form where possible
  • regularly clean the work area to remove any build up of fibres and/or dust. Visible waste materials should be removed promptly to avoid being trampled and spread about
  • clean with an industrial vacuum cleaner. Wet mopping and wiping is acceptable if this is not possible.
  • keep amenity rooms as free as possible from fibres and dust
  • place waste in plastic bags or other containers which prevent fibre and dust emission, and dispose of them in accordance with requirements of the local environment protection and waste disposal authorities
  • provide adequate washing facilities on site to wash the skin, and to treat dust in the eyes
  • provide appropriate instruction, training and supervision to enable workers to safely perform their tasks. The training should include instruction in the:
    • importance of controlling the level of glasswool and rockwool fibres and dust in the atmosphere to the lowest workable levels
    • control measures that are in place
    • safe work practices which must be followed
    • selection, wearing and maintenance of PPE.

Personal protective equipment (PPE):

PPE should be readily available in the workplace.

  • Respirators:
    • Class P1 and Class P2 efficiency is adequate for virtually all aspects of work involving glasswool and rockwool to ensure a worker’s exposure is kept to a a time weighted average (TWA) of < 2 mg/m3 inhalable dust. The choice of Class P1 and P2, and disposable or non-disposable, is often determined by practical considerations such as worker comfort or preference and the reliability of maintenance.
    • information about the selection, maintenance and performance of all types of respirators is found in Australian Standards AS 1715:2009 selection, use and maintenance of respiratory protective equipment and AS 1716:2012 respiratory protective devices.
    • respirators should be correctly fitted. The actual protection provided is very much determined by the quality of the facial seal and the degree of any resultant leakage from, eg: beards and the wearing of glasses or goggles.
    • respirators should be maintained in good condition and kept in clean storage when not in use.
    • replaceable filters and cartridges should be replaced regularly, in accordance with guidelines issued by the manufacturer.

    It takes only short periods during the workday of not wearing a respirator to erode the protection afforded even by high efficiency filters.

  • Clothing should be loose fitting, long sleeved, long legged garments or disposable overalls:
    • if not disposable, the clothing should be washed regularly and separated from other laundry to avoid cross contamination and subsequent skin irritation of non-workers
    • consider the type of material chosen to avoid undue heat stress and general discomfort for the wearer.
  • Gloves as specified in the SDS
  • Safety goggles or face shields (especially for overhead work)

5.2 Specific additional work practices for unbonded glasswool and rock wool insulation materials

Wet Spray: The following additional handling and installation procedures are recommended for wet-spray rockwool material:

  • place bags into a hopper before slitting open
  • avoid excess shaking of bags and the production of unnecessary dust
  • fold used bags and store in waste container
  • take care to ensure that the material is sprayed only in the desired area, and
  • a cleaning and maintenance program for the machine and adjacent area, including vacuuming or wet mopping and wiping, should be available.

Loose Fill: Work with loose fill has the potential of creating relatively high airborne fibre levels, therefore the product should be handled more carefully. The following additional handling and installation procedures are recommended for loose-fill rockwool material:

  • avoid unnecessary disturbance, eg: tearing, of the product
  • where packing down is required, it should be done only to the required degree so as to minimise the disturbance of the product
  • fold empty bags and store in a waste container
  • ensure adequate sealing of the application site for overhead applications or protection of workers below, and
  • remove excess material from the work area at completion of job.

Dry Spray: This work has a potential of creating relatively high fibre levels and therefore these additional recommended work practices should be closely followed.

  • avoid unnecessary disturbance, eg: excess shaking of bags; tearing of the product
  • place bags into a hopper before slitting open
  • fold used bags and store in waste container
  • no spraying to commence until the nozzle is securely in the target area and the spray is to be terminated before the nozzle is removed from the target area
  • no material should be left in the machine unless the machine is adequately covered
  • cleaning and maintenance of the machine and adjacent area should be carried out at the completion of the job.

5.3 Specific work practices for the removal of glasswool and rock wool insulation materials

Procedures to be used for the removal of glasswool and rockwool insulation depend on the form of the original insulation wool installed.

5.3.1 Bonded glasswool and rockwool insulation:

Any physical abrasion, including cutting, should be kept to a minimum during removal. If there is minimal physical abrasion, the removal can be performed in a dry condition. Only in circumstances where heat or other causes have made the bonded material attach itself to the substrate should physical abrasion take place. If this occurs, removal should be performed as for unbonded glasswool and rockwool removal.

5.3.2 Unbonded glasswool and rockwool insulation:

Removal of unbonded material is more dusty and difficult. The unbonded material should be thoroughly wet down before removal takes place. Dry removal may be necessary when there are electrical and heat hazards. Increased respiratory protection may be necessary when working in enclosed or poorly ventilated spaces or where the insulation has undergone physical change.

6. Further information

1 May 2015

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