MEASUREMENT OF AIRBORNE CERAMIC FIBERS IN MANUFACTURING AND PROCESSING FACTORIES

Airborne aluminium-silicate ceramic fibre concentrations and fibre siz es in work environments were measured. Samples were collected from two factories (A and B), including fibre manufacturing and processing wor kplaces. In each workplace, five measuring points were chosen for the stationary sampling. The personal sampling was also carried out simult aneously. The fibre concentration was determined by counting collected fibres under the phase contrast optical microscope and the diameter a nd length distributions were obtained from photographs taken under a s canning electron microscope. The geometric average concentrations by t he stationary sampling were 0.10-0.66 fibres per cm(3) (f cm(-3)). The personal exposure levels for these factories were twice, or more, the average fibre concentrations by the stationary sampling. The co unt m edian diameter (CMD) and the count median length (CML) of the fibres i n the manufact uring workplaces were 1.16 and 14.7 mu m in factory A, and 0.86 and 12.5 mu m in factory B, respectively. The geometric stand ard deviation (GSD) of the fibre length was generally larger than that of the fibre diameter. The values of CMD, CML and GSD by the personal sampling were almost identical with those by the stationary sampling.