Effect of asbestos sampling methods on fiber dispersion on membrane filters

Includes bibliographical references (pages 31-33)There are many ways in which to collect and analyze airborne asbestos dust. This experiment centered on evaluating the uniformity of fiber dispersion on membrane filters when collected by the NIOSH method and two other methods. Using a dust generator, a mixing chamber, and sampling trains, asbestos fiber samples were collected on membrane filters, using each of the three methods. Wedges cut from the filters were analyzed by phase contrast microscopy to determine the average fiber counts (AFCs) on their inner and outer halves. The difference (D) between both halves was then calculated.\ud From this data, 1) an ANOVA test was employed to determine whether any method had a mean difference (D) which was significantly different from the others, and 2) t tests were used on counts obtained from each method to determine if the average inner area counts (I) were significantly different from the average outer area counts (0). No significant difference was found between the results obtained by the different methods. Furthermore, there was no significant difference between the fiber counts obtained from the inner versus the outer aspects of filters from a given sample method