Rj. Lee et al., INTERLABORATORY EVALUATION OF THE BREAKUP OF ASBESTOS-CONTAINING DUSTPARTICLES BY ULTRASONIC AGITATION, Environmental science & technology, 30(10), 1996, pp. 3010-3015
Measurement of asbestos in settled dust has been suggested as a surrog
ate for past and potential future airborne exposures. While conceptual
ly appealing, identification and quantitation of those respirable part
icles that either were airborne or could become airborne through re-en
trainment are complex and difficult tasks: Round robin testing of a dr
aft ASTM method [The method has recently been balloted and passed by A
STM as Method D-5755.] for determining asbestos in dust was performed
to assess the variability of the method and the impact of large, non-r
espirable asbestos-containing particles on the reported numerical conc
entration of respirable asbestos structures. Tests conducted using sin
gle, non-respirable particles of asbestos or asbestos-containing mater
ials (ACM) indicate that these large particles can give apparent conce
ntrations of asbestos in the dust on the order of millions of structur
es per square centimeter. Coefficients of variation (CV) ranged up to
2 for these tests, primarily the result of variable application of the
indirect preparation procedure. A second series of tests was conducte
d using simulated building dusts. ACM dust was blown throughout a cont
rolled chamber, and the resulting settled dust was sampled and distrib
uted to participating laboratories. These results indicate that the in
terlaboratory CV is similar to that of the first tests, but can be red
uced to 0.8 if restrictions are placed on the indirect sample preparat
ion procedure. There was no statistically significant difference in th
e concentration of asbestos collected from three different surfaces, b
ut this is the result of limited data and highly variable results. Ove
rall, these tests indicate that the analysis of surface dusts using in
direct sample preparation should be limited to qualitative evaluation
as to the presence of asbestos in the surface dust.