Document KGmXr7zx70E0y4ErodrXYZa96

46 - 5. Conclusions Due to the smell site Of the^asbestos fibres present in the ambient environment, electron microscopy plays an important role in their qualitative and quantitative deterroination. For the same reason large magnifications have to be used, which means that only very small samples can he investiga ted in a reasonable time resulting in relatively rough estimates (order of magnitude) of the asbestos concentrations which hove to be determined. It should be noted that there is a growing tendency to report investi gations in weight concentrations as there exists a tendency for larger fibres to fall apart into small fibrils during the qualitative assessment of the concentration. Sizes determined during the qualitative investigation give an indication of the fibre size as found in the enviionment .nd .should be reported separately. Without this information the conversion of weight con centration (weight of fjbrcs/volume of air) into a numerical concentration (number of fibres/volume of air) and vice-versa is not partible. The F..Workshop on metrology in 1916 concluded that.: Mr 1. cnt air is and has been monitored for asbestos in sonic of the Member States, but cmly a few of the monitoring programmes arc systematic in nature and carry out a detailed cy.?.r..i :.-ati or> of the nature of the fibres. '1. In view of the possible impr.rtc.nce, from the public health tt.:*.ipcint, to determine and identify fibres in air which arc- sub-::.i ci cseopic in size, analytical techniques using the electron microscope are required. The availability of analytical facilities for such measurements being limited and each determination being time consuming and costly, the num ber of analyses, even in a comprehensive monitoring programme, most be limited. ^ j c> prevent misunderstandings it rh.:-.:)d bopeir.v^p oub-xhhat this statement concerns the ambient c:ivi ron:.cnt. Twi the jiru.m- .*! lo vable concentrations which are tpplTc'able' undVr'Vcouprtt; cnal ccr.iiticns Ihcrc is an increasing tendency to fellow the mevhwJs by UM Ft-iory j;):.p*_''*.orete, reporting the ronemtr aliens in filnes/cm . 3. Such me potentf 4. The mo.* filter, to red for on Gravi rr. count a selc 5. An int to gai may b parat The *. J outi Wia ter C. Drink Ki-rjic 7. The : wfitej tap i tO it the . evil B. The * sbf f ha-it; i i 8001 ft741 PRODUCED BY FORD