A comparison of the closed-face cassette at different orientations while measuring total particles.
Cook-DM; Sleeth-DK; Thiese-MS; Larson-RR
J Occup Environ Hyg 2015 Mar; 12(3):199-204
The current method for sampling aerosols using the 37-mm closed-face cassette (CFC) sampler is based on the orientation of the cassette at approximately 45 degrees from horizontal. There is some concern as to whether this method is appropriate and may be underestimating exposures. An alternative orientation at approximately 0 degree (horizontal) has been discussed. This research compared the CFC's orientation at 45 degrees from horizontal to the proposed orientation at horizontal, 0 degree in a controlled laboratory setting. The particles used in this study were fused alumina oxide in four sizes, approximately 9.5 microm, 12.8 microm, 18 microm, and 44.3 microm in aerodynamic diameter. For each test, one aerosol was dispersed in a wind tunnel operating at 0.2 m/s with samplers mounted in the breathing zone of a rotating mannequin. A sampling event consisted of four pairs of samplers, placed side by side (one pair at 45 degrees and another at 0 degree cassette orientation), and exposed for a period of 45 minutes. A total of twelve sampling events, three sample events per particle size, were conducted with a total of ninety-four samples collected. Mass concentration measurements were compared to assess the relationship between the sampler orientations of the cassettes. In addition, the relationship between the mass collected on the cassette filter and on the interior walls of the cassette was also assessed. The results indicated that there was no significant difference between the measured concentrations based on the orientation of the CFC's. The amount of mass collected on the interior walls of the cassettes were relatively low (<5%) compared to expected (up to 100%) wall losses for both orientations.
Sampling-methods; Particulate-sampling-methods; Particulates; Samplers; Aerosol-particles; Aerosol-sampling; Analytical-instruments; Exposure-assessment; Air-sampling-equipment; Equipment-reliability; Laboratory-testing; Particle-aerodynamics; Breathing-zone; Filters; Analytical-processes;
Author Keywords: aerosol; closed-face cassette; particles; sampler orientation; wind tunnel
Darrah K. Sleeth, Rocky Mountain Center for Occupational and Environmental Health, Department of Family and Preventive Medicine, University of Utah, 391 Chipeta Way, Salt Lake City, UT 84108, USA
Journal of Occupational and Environmental Hygiene
University of Utah, Salt Lake City, Utah