Document ZoVwY76MmBJOkZXR2aGjM567

-7 2) give some indication of fiber counts from personal samples 3) determine some index which may be used in the absence of better information to estimate the proportion of asbestos in a mixed dust exposure. From this study the following relationships were determined: Light Field Technique Membrane Filter Method Fiber Length 1 nppcf 1 nppcf 1 nppcf 10 fibers/ml 6 fibers/ml 3 fibers/ml all fibers > 5 yo > 10 yjn This study shows the effect on the TLV intended changes of 1968 1969 of 2 mppcf or 12 fibers/ml for fibers greater than 5 ym in length. Based on the established TLV of 5 nppcf still being used at the time of the study.the following equivalent relationships can be stated: Total fibers - 50 fibers/ml Fibers longer than 5 ym - 30 fibers/ml Fibers longer than 10 ym - 15 fibers/ml If the suggested level of exposure was to be limited to 5 fibers/ml for fibers greater than 5 ym in length, it can be seen that the iaplmger technique would require a TLV of less then 1 appcf. This would be near the lower practical limit of sensitivity of the Inplnger technique. Accurate measurements would be very difficult by the lapinger method. Another fact was that this relationship was obtained for asbestos textile win* and would not necessarily be valid for other industries. In fact, the results could not be related from one plant to another far the seme operation. > 0(/p 902032