Asbestos-containing millboard was once widely used in the construction industry due to its flame-resistant properties, and commonly used to line compartments containing heat or spark-producing electrical equipment. In particular, asbestos-containing millboard surrounded reheating banks or coils throughout the ductwork of air conditioning units.
While there have been successful undertakings to replace air conditioning systems and the asbestos-containing millboard over the years, many systems still remain, often unknown to their owners. As older buildings undergo retrofitting, many elements of mechanical plant are being decommissioned and removed.
Unfortunately, this exposes a variety of contractors and sub-contractors, as well as younger workers unfamiliar with older systems, to potential hidden dangers.
Factors and risks to consider
Asbestos-containing materials, such as millboard, that are intact and in good condition are not hazardous to building occupants under normal conditions. However, asbestos becomes a health risk when fibres are released into the air and inhaled. The length and frequency of exposure may impact the risk of developing asbestos-related diseases such as asbestosis, mesothelioma and lung cancer.
The main concern with old systems is to avoid accidental or inappropriate disturbance without correct safety procedures in place.
The Work Health and Safety Regulations 2012 (SA) require an inspection of the workplace to identify asbestos in buildings (regulation 422). This includes the requirement for building owners to keep an accurate register of all asbestos containing materials on the premises. Where asbestos cannot be accessed, its presence can be assumed.
Millboard lining, as well as other suspected asbestos-containing components of old heating and air conditioning systems, should be identified as containing asbestos and removed prior to demolition (regulation 452) or refurbishment (regulation 456), so that the exposure risk is minimised.
If refurbishment or replacement of the heater bank ductwork for a building has not taken place in the past 30 years, we recommend the following action:
- check the building’s asbestos register for a note that millboard lining in the heater banks has been identified or removed
- if not identified or removed, add the issue to the building asbestos register for future workers
- if accessible, label the ductwork adjacent to the heater banks in line with the requirements for labelling asbestos-containing materials (regulation 424).