Abstract
ASTM Standard D5755 “Standard Test Method for Microvacuum Sampling and Indirect Analysis of Dust by Transmission Electron Microscopy (TEM) for Asbestos Structure Number Concentration” uses a microvacuuming sampling procedure and transmission electron microscopy analysis to (a) identify asbestos in surface dust and (b) provide an estimate of the surface loading of asbestos in the sampled dust reported as the number of asbestos structures per unit area of sampled surface. In a precision study of the method, ten laboratories analyzed chrysotile asbestos-containing World Trade Center dust that had been resuspended in a test room and collected off of non-asbestos floor tiles following the microvacuum cassette (microvac) collection procedures described in ASTM D5755. Each laboratory analyzed the same sample twice. The Inter-Laboratory Studies (ILS) Group of ASTM International performed the statistical examination of the data set and found a repeatability limit (r) of 61.80 and a reproducibility limit (R) of 239.30. The study data was also used to calculate coefficients of variation of 0.15 intra-laboratory and 0.6 inter-laboratory.
