Manufactured Mineral Fibre (MMF)
Definition
Man-made fibrous materials (glass wool, rock wool, ceramic fibre) used as insulation; resembles asbestos morphologically but has different elemental composition (no iron in glass wool) and solubility, and is not subject to the same regulatory limits.
- Examples
- Glass wool, rock wool, ceramic fibre
- Use
- Thermal and acoustic insulation
- Distinguishing test
- Elemental composition, e.g. no iron in glass wool
- Regulatory status
- Not subject to asbestos regulatory limits
Common questions
Why can MMF be mistaken for asbestos under a light microscope?+
Both are fine, fibrous materials with similar diameters and aspect ratios that can look alike under polarised light microscopy, which is why elemental analysis such as SEM-EDX, capable of detecting the compositional differences between mineral wool and asbestiform minerals, is needed for a confident distinction.
Does a lower regulatory limit for MMF mean it carries no health risk?+
No, MMF exposure is still associated with respiratory irritation and is monitored under general workplace dust and fibre exposure limits; it is regulated less strictly than asbestos because its fibres are generally more soluble and biopersist in tissue for a shorter time, not because it is inert.
Related terms
- Asbestos
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- Fly Ash
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- Geoforensic Location Indicator
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- Phase Contrast Optical Microscopy (PCOM)
- The WHO-recommended routine method for counting airborne asbestos fibres in occupational and environmental samples; counts fibres visible at 400-500x magnification, with confirmation...
- SEM-EDX
- Scanning electron microscopy with energy-dispersive X-ray spectroscopy. The electron beam excites characteristic X-rays from each element present in the target grain, giving...