Document ExNj23dZLR8vnk9jBrBmNL1Yg

Minutes of Meeting Asbestos Study Committee -4- August 17, 1972 SAMPLING FOR ASBESTOS FIBER COUNTING ilr. Stone questioned the possible movement of asbestos Inside the filter sample when sent to th& lab for examination. Hr. Weaver indicated that this possibility vas quite remote. Apparently the question arose after as OSHA visit to the aether*s plant. In response to a question, one tneober Indicated it takes about tvo months from the OSHA sampling until the OSKA report is received. Further, it vas indicated that the company hears if it is to be cited and not if the conditions are satisfactory. The OSHA regulations call for an eight hour time weighted average (TWA) for the measurement of air. borne concentration of asbestos fibers. One member indicated that he runs his sample test for a continuous four hours to compute the concentration. With a continuous four hour sampling, there are sometimes reactions from the shop people. Returning to the question on sampling for fiber counting, OSHA recomnends a full straight eight hour sample. It vas indicated they used 8 filters during this continuous sample. A member suggested using 90 minute sampling for most arsss, or s complets job cydt if it took longer then 90 minutes. He recommended four hours of sampling for specials. A member questioned as to whit minimum time vas necessary in sampling to determine the peak concentrations that cannot exceed ID fibers per ec. Ho specific answer vas givsn, but Weaver indicated some sampling procedures which he felt were optimum for counting fibers entrapped by the filter. The number of tests for various conditions is suggested la this tabulation. One condition Is where you ere measuring friction materials with asbestos In the compuad, and the other is for areas vhert you ara handling ell asbestos. Optimised time for fiber collection - depending on TWA fiber per cc concentration expected in area. (Optimum for counting fibers on the filter) Friction Materials TVA Fibers t>er ee Ontlmum Humber of Tests All Asbestos TWA Fibers per cc 0- 3 5-10 10-13 1J-20 - 1-8 hr. test 2-4 hr. tests 3 tests, 3,3,2 hrs. 4-2 hr. tests 8-1 hr. tests 0- 3 3- 6 6- 9 9-13 13-20 The question arose concerning the sample* where one is trying to pick up asbestos for counting. What about tha oclf^Wiftrials In braka lining that are not?ons)erf hazardous? Might these not be counted on the filter as veil es esbestos? One ensver that is Indicated for the skilled laboratory nan making the examination is that ha should be able to distinguish between asbestos fibers and other materials. Further, one can go to 300X on the microscope and get a closer look at the materials picked up on the filter. Dr. Spurgeon indicettd that one can usa low temperature ashing to remove resins and other organic materials (primarily friction dust).