AIRBORNE FIBER CONCENTRATION DURING STANDARDIZED BUILDING INSULATION WITH BONDED MAN-MADE VITREOUS FIBER INSULATION MATERIAL HAVING DIFFERENT NOMINAL DIAMETERS AND OIL CONTENT

A method for a priori determination of fibre concentration during work with man-made vitreous fibres (MMVF) is suggested as an alternative t o measurements during actual use at construction sites or elsewhere. I t is based on a standardized insulation job in a test room. The proced ure is described. A theoretical sensitivity analysis showed that the e ffect of small changes in experimental parameters would have only a mi nor influence on the measured concentrations. Measured concentrations of respirable fibres were used to develop a model for fibre concentrat ion as a function of bulk material characteristics, based on simple ph ysical arguments. The parameters were total fibre length per weight of bulk MMVF and amount of oil per total fibre surface. By including the bivariate log-normal fibre size distribution in the model, it could b e shown that fibre concentrations could increase with increasing nomin al diameter. The geometric standard deviation of the bulk fibre diamet er distribution as a primary variable plays a significant role. A part ial least-squares (PLS) analysis including seven variables identified two principal components which could explain 65% of the observed airbo rne respirable fibre concentration The approach thus can be used for r anking insulation wool material on a relative scale. The test represen ts a worst case scenario, and can be used for exposure assessment.