A field comparison of respirable dust samplers

A study evaluated differences between respirable dust concentrations measured with three currently available cyclone samplers in a field setting. Comparisons also were made between cyclone and personal cascade impactor results. The cyclones selected were designed for sampling according to one of three respirable dust criteria: British Medical Research Council (BMRC) (D₅₀₎ = 5 μm), previous American Conference of Governmental Industrial Hygienists (ACGIH) (D₅₀ = 3.5 μm), and proposed ACGIH (D₅₀ = 4 μm). Samples were collected by placing two each of three brands of cyclone, two personal cascade impactors, and two total dust samplers on a tripod-mounted boom assembly. The apparatus sampled abrasive blasting operations. A significant difference was detected between the results of the BMRC and proposed ACGIH-type samplers and between the BMRC and previous ACGIH-type samplers. The BMRC-type sampler consistently yielded the highest average respirable dust concentrations, followed by the proposed ACGIH and previous ACGIH-type samplers. Cascade impactor results were converted to respirable dust concentrations using the appropriate collection efficiencies for comparison to cyclone results. The differences between the cyclone and cascade impactor results were not statistically significant at the 5% level. Results reiterate that important differences exist between respirable dust sampling methods, and that when sample results are reported, the type of sampler used, the flow rate, and the respirable criteria with which the sampler was designed to conform should be specified.