Must admit, this form of Insulation has not been on my "radar" as being a respiratory problem causer ?
It appears very low when compared to [say] Asbestos?
Just done a [very] quick check on this stuff H&Safety site states.
Loft insulation
7. In the past, there has been some concern about the possible risk to householders arising from the presence of MMMF loft insulation, usually in the form of mineral wool. In 1987, the DoE undertook work to collect data to establish the extent of householders' exposure to MMMF from this source, and it then asked the Department of Health's Committee on the Carcinogenicity in Food, Consumer Products and the Environment (COC) to review the evidence. On completion of the COC's work, the Secretary of State for the Environment made a statement in the House of Commons and issued a Press Release dated 1 December 1987 recording the COC's assessment of the risk to health from MMMF loft insulation, DIY installation and subsequent disturbance. As a result of the COC's work, the DoE Press Release was able to reassure householders that they need not be concerned about the presence of MMMF in their lofts, about installing it themselves or about doing DIY work in lofts insulated with MMMF. However, it recommended use of an appropriate mask for installation work, ie one conforming to BS 6016 or BS 2091 (see para 15), and the use of gloves when handling the material to avoid skin irritation.
8. More recently, the HSE has undertaken studies to determine fibre levels arising from the presence of MMMF loft insulation in UK dwellings. The results from these studies have also been assessed by the COC who again concluded that the MMMF in the lofts of dwellings presented no significant hazard to householders.
9. Inspectors are reminded that during 1988/89, SPNs were made to contractors installing MMMF loft insulation to promote observance of the (then) gravimetric Control Limit, and to monitor dust levels produced by the work. The results of the exercise and implications for inspectors are set out in OC 267/1
There is no information on the above on the Cancer UK web site.
If it were me, I would add a non irritant insulation on top of the present Glass wool??
Ken.