Document 5Lr6BQD6X85NDJJQLz0ZnbdJe

2J8 .... ' .. **; **# * '/ i '% i> }**,$* * * * . i 4L -r V: *r..s >. -> ' > :,?; - v .,*r ,, r.. A ',*' . - * * * ' O. : ' ,r.*.. . =v^>r*--..- ' .*. -? K -' v;-* ..X June, 1973 \ | . **** f? w * .V??e'-*' IN 3-Vi; . / .; *. , . . -- / yv _ Figure 6. Asbestos and non-asbestos particles before the application of refractive index liquid. JOOX. (Sample D). TABLE nr Data from JAM Analysis Sample C % of Non-Asbestos. 0 % of Particles 5 *m or > 12.7 Fiber Count. ml 5 iim or > 0.6 Average Panicle Size . 2.9 inn ' D 31.9 3.3 1.1 2.3 itm Discussion The .present use of the "total fiber count" system:' as recommended by the NIOSH for overall evaluation of asbestos concentrations , coupled with the "open-face" filter collection technique can be a source of error in the ; measurement of exposure to asbestos. The --low-number-of total particle xount and an approximately 1/9000 analyzed area of the " ^.'^^4 E. v mmgra r Figure 7. Same area a^ shown in Figure .6 after; application of the refractive index liquid, iOOX. (Sahiple D). total filter surface (as specified by NIOSH) . along with the non-uniform particle distribu tion cannot produce 4 reliable analysis. The presence of asbestos resembling fibers also adds to the problems: The accuracy Of the IAM method relies on two important factjs, the large number of particles counted, an$ the large number of areas covered. It is also important that within these areas: aUj particles are counted. These factors will minimize the uncontrolla ble errors: There is no correlation between the results obtained bjy IAM and the micro scope counts of Samples C and D (Tables/ II and III). This is' due to the fact that Sample. D is .composed to .almost one-third of non-asbestos particles.. 8000 033? HFM - 002041