Size distributions of airborne superfine man-made mineral fibers determined by transmission electron microscopy.

A survey was conducted to determine the size distribution of airborne man-made mineral fibers in three factories using bulk materials which contain many fibers with diameters less than 0.3 micrometers. Personal samples were taken in two of the factories visited. In all the cases a full length and diameter distribution, determined by transmission electron microscopy, are presented. Median diameters ranged from 0.1 to 0.3 micrometers and, as a result, a substantial proportion of the fibers would not be detected using light microscopy or scanning electron microscopy even for fibers longer than 5 micrometers.