The “natural” insulation industry has done lot to frighten people about mineral and glass insulation to promote their industry. In the Yellow Pages, natural insulation companies often have the spurious claim “contains no asbestos or fibreglass”. Guilt by association. One manufacturer in the US even set up a bogus organisation called “Victims of Fibreglass”. Natural insulation has the treated with chemicals to make it fire and rot resistant. Not very natural.
For a fibre to be breathed in and deposit deep in the lungs it had to be less than about 3 microns diameter. Human hairs are around 40 microns diameter). Glass fibres of this size dissolve in lung fluid, so are removed before they can exert any toxicity. The Australian Wool Board found wool fibres around 20 microns to be itchy – a function of their diameter and stiffness.
That’s why ‘hair shirts’ are itchy and that cheap pullover is almost unwearable. This mechanical effect probably accounts for the itchiness of some insulation fibres, so it is a good sign and indicates that the fibres are too coarse to be respirable.
