Last week I had finished fitting a mains board inside a lighthouse and had started to clip the flex for a tubular heater. First bash of the hammer on the cable clip produced a large cloud of dusty debris that came outfrom behind the wood pannels onto which the flex was going to be held. I was coated with the stuss and breathed in a load to the extent that my voice was hoarse for the remainder of the day. I followed procedure and phoned my findings into head office suspecting that it may be an asbestos containing substance. To cut out all the intervening goings on air samples were taken by an analyst and found to contain NO fibres but solid samples were taken aswell and found to be positive for Crysotile. I have been told that as no airborne fibres were foind I have not been exposed !!! Surely the massive lung fyll of the dust cloud proves otherwise. Thoughts please. A.