Man-made mineral fibres, MMF for short, are the most widely used insulation material in Austria. Glass wool is spun from molten glass, stone wool from molten rock, slag wool from blast-furnace slag. In themselves not a problem. What matters is the age: if a renovation turns up yellowish, brittle insulation mats in a suspended ceiling or roof, a closer look is worthwhile, because old and new mineral wool differ fundamentally in health terms.
Old or new: the decisive question
What matters is the biosolubility of the fibres. Mineral wool produced before about 1996 contains biopersistent fibres. They are long and thin (a so-called WHO fibre is longer than 5 µm, thinner than 3 µm and at least three times as long as it is thick), reach deep into the lung, and the body breaks them down only slowly. Fibre dusts from such old mineral wool are classified as carcinogenic under the European substance classification. Modern mineral wool, by contrast, is biosoluble: the fibres dissolve in the body comparatively quickly and are not classified as carcinogenic. Since about 2000 only such products have been on the market, recognisable by the RAL quality mark "Erzeugnisse aus Mineralwolle". (The IARC classifies the common insulation wools as not classifiable, Group 3; what is decisive for the careful handling of old mineral wool is its classification under substance law as carcinogenic.)
The question at every renovation is therefore: old or new?
Where old MMF sits
In buildings constructed between about 1965 and 2000, old mineral wool typically sits in these places:
- between-rafter insulation in the roof structure
- cavity insulation in lightweight walls
- pipe insulation in the basement
- impact-sound insulation under screeds
- suspended ceilings in office and commercial buildings
The material is often yellowish, brittle and dusts when touched. It is precisely this dusting that is the problem, because it releases fibres into the room air.
When it becomes a problem
- Old MMF in closed cavities (wall, roof, under screed): no acute need for action as long as the insulation is not disturbed and there is no open connection to the living space.
- Old MMF in open contact with the room air (open ceilings, visible insulation): a room-air measurement provides clarity.
- Renovation planned, old MMF must come out: protective measures are mandatory. Old mineral wool is hazardous waste and does not belong in household refuse.
How to determine it
If insulation looks old and carries no quality mark, a material sample gives certainty. In an accredited laboratory it is determined whether biopersistent fibres are present. Sampling on one's own and ripping it out without protection are not advisable, because this releases exactly the fibre-containing dust one wants to avoid. This belongs, like the remediation itself, in expert hands.
The legal framework
Old, biopersistent mineral wool is classified as carcinogenic (on the basis of the EU substance regulations, in Austria via the Limit Values Ordinance). For work on such material a minimisation requirement therefore applies: fibre release is to be kept as low as possible, with containment, extraction and personal protective equipment. The removed material is to be disposed of as hazardous waste, not via household refuse. Modern, biosoluble mineral wool is not subject to these special requirements.
MMF is not asbestos
The comparison with asbestos is often drawn, and the differences are important. Asbestos fibres are considerably more dangerous, finer and more durable, and they require stricter remediation procedures (→ Recognising asbestos). With old mineral wool the risk is lower and the measures are simpler. Still, it should not be ignored, especially during a loft conversion or a full renovation, in which a lot of old material is moved.
Old insulation rarely comes alone. In buildings of the same decades there is often also PCB in elastic joints and, in buildings from before 1990, asbestos in boards and adhesives.
Sources
- IARC, Monograph 81 (2002): glass, stone and slag wool as not classifiable (Group 3), only special-purpose and ceramic fibres as Group 2B
- EU Directive 97/69/EC (classification of biopersistent fibres) and Directive 2004/37/EC, implemented in Austria via the Limit Values Ordinance
- RAL Quality Association Mineral Wool, quality mark "Erzeugnisse aus Mineralwolle" (biosolubility)
- Bavarian State Office for the Environment, „Künstliche Mineralfasern": lfu.bayern.de
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