| Autor: |
Pang, Thomas, Schonfeld, Fay, Patel, Kishore |
| Zdroj: |
American Industrial Hygiene Association Journal; July 1988, Vol. 49 Issue: 7 p351-356, 6p |
| Abstrakt: |
Replicate aliquots of an aqueous suspension of amosite asbestos were filtered through either polycarbonate or cellulose membrane filters. The polycarbonate filters were prepared using a direct transfer (DT) method and analyzed using transmission electron microscopy (TEM) and phase contrast microscopy (PCM); the cellulose filters were treated and analyzed using National Institute for Occupational Safety and Health (NIOSH) Method P&CAM 239. Compared to the results of the TEM examination, approximately 93% and 146% of the amosite fibers longer than 5 µm were detected using the DT-PCM and NIOSH methods, respectively. Compared to the previous recoveries of chrysotile fibers of 47% by the DT-PCM method and 13% by the NIOSH method, the improvement in accuracy of the 2 methods in the analysis of amosite fibers was due to the fact that the difference in refractive index between the amosite fibers and the background was approximately 0.21, such that more than 98% of the amosite fibers longer than 5 µm were clearly visible by both methods. The over-estimation of the number of fibers by the NIOSH method may be attributed to analyst error in sizing fibers with lengths in the 4 to 5 µm range. Various analyst errors associated with the DT-PCM method are addressed. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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