Posted By Diane Thomason I've received this query from an electrical technician in one of our departments: "Most of the ovens/heaters/mantles which require my attention have the heating elements encased in highly insulating but irritant fibre insulation. When replacing the heating elements it is often necessary to remove a large part of this insulation to get to the element (and it's associated wiring) which leads to a large amount of invisible fibres released into the immediate vicinity. When I first encountered this it caused me to cough while exposed, my response was to wear a disposable particle mask to complete the job and on subsequent similar jobs. Skin irritation is not a problem as I always wear gloves. My question is: What form of extraction/ventilation is recommended, bearing in mind that some larger ovens need to be serviced in situ. Can this be vented outside? We have the facilities to construct directable fume extraction for the workshop area, there is also access to fume cupboards but as the smaller units are serviced on a fully equipped test bench it would be awkward without having a dedicated fume cupboard. The insulation is described as "Mineral Wool"in the case of the rockwool but also reference to "Ceramic Fibre". The Ceramic Fibre is a solid insulation used instead of rockwool on the later heaters which emits dust if disturbed. In the specification for the Electrothermal Cartridge type mantles a note mentions the risk from "insulation made from Refractory Ceramic Fibres, EU directive EEC/67/548 class 2 carcinogenic" There is also a risk of unknown vapours from spilled chemical residue being re-heated when the heaters are tested." I will of course investigate what risk assessments have been carried out, but does anyone have specific advice on control measures for this type of fibre insulation under these circumstances? I looked up an MSDS for ceramic fibre and it does say that chronic exposure to the dust is hazardous and that it is a potential carcinogen. Thanks Diane