Submicroscopic fibres in industrial atmospheres

Evidence obtained from a large number of samples of airborne dust from a number of different asbestos-using industries suggests that it would be possible to use gravimetric sampling to estimate the respirable fibre concentration of the atmosphere around specific operations. The precision of this method of estimating airborne fibre concentration is shown to be approximately the same as the variation between different counters using existing counting techniques. Tables are included showing the fibre content of industrial dusts in millions of fibres/mg of dust and the factors (with 95% confidence limits) by which light microscope counts should be multiplied to give the true counts of fibres longer than 5 micrometers.