Personal and area air samples were taken at a scrap lead smelter operation in a bullet manufacturing facility. Samples were taken using the 37-mm styrene-acrylonitrile closed-face filter cassette (CFC, the current US standard device for lead sampling), the 37-mm GSP or "cone" sampler, the 25-mm Institute of Occupational Medicine (IOM) inhalable sampler, and the 25-mm Button sampler (developed at the University of Cincinnati). Polyvinylchloride filters were used for sampling. The filters were pre- and post-weighed, and analyzed for lead content using a field-portable X-ray fluorescence (XRF) analyzer. The filters were then extracted with dilute nitric acid in an ultrasonic extraction bath and the solutions were analyzed by inductively coupled plasma optical emission spectroscopy. The 25-mm filters were analyzed using a single XRF reading, while three readings on different parts of the filter were taken from the 37-mm filters. The single reading from the 25-mm filters was adjusted for the nominal area of the filter to obtain the mass loading, while the three readings from the 37-mm filters were inserted into two different algorithms for calculating the mass loadings, and the algorithms were compared. The IOM sampler was designed for material collected in the body of the sampler to be part of the collected sample as well as that on the filter. Therefore, the IOM sampler cassettes were rinsed separately to determine if wall-loss corrections were necessary. All four samplers gave very good correlations between the two analytical methods above the limit of detection of the XRF procedure. The limit of detection for the 25-mm filters (5 microg) was lower than for the 37-mm filters (10 microg). The percentage of XRF results that were within 25% of the corresponding ICP results was evaluated. In addition, the bias from linear regression was estimated. Linear regression for the Button sampler and the IOM sampler using single readings and the GSP using all tested techniques for total filter loading gave acceptable XRF readings at loadings equivalent to sampling at the OSHA 8-hour Action Level and Permissible Exposure Limit. However, the CFC only had acceptable results when the center reading corrected for filter area was used, which was surprising, and may be a result of a limited data set. In addition to linear regression, simple estimation of bias indicated reasonable agreements between XRF and ICP results for single XRF readings on the Button sampler filters, (82% of the individual results within criterion), and on the IOM sampler filters (77% or 61%--see text), and on the GSP sampler filters using the OSHA algorithm (78%). As a result of this pilot project, all three samplers were considered suitable for inclusion in further field research studies.

Numerical calculations were conducted to simulate air and particle behavior near and into the inlet of an aerosol sampler in order to determine sampling efficiency performance. This was done with the pre-verified commercial computational fluid dynamics (CFD) software package, FLUENT (Fluent, Inc., Lebanon, NH, US). Air flow behavior was calculated for steady-state conditions approaching and flowing into 3D geometries of an aerosol sampler free in the air that was similar in dimension to two commercial samplers, namely the Gesamtstaubprobenahme sampler (GSP) and the conical inhalable sampler (CIS). Particle trajectories were calculated in a Lagrangian reference frame on the resulting velocity fields. Based on the particle trajectories, sampling efficiencies were calculated and compared to those reported in the literature for a CIS aerosol sampler. They were found to have similar overall trends for particle sizes up to 21 µm. Using a correction factor, agreement The findings and conclusions in this report are those of the author and do not necessarily represent the views of the Centers for Disease Control and Prevention or the National Institute for Occupational Safety and Health. Mention of a commercial product or trade name does not constitute endorsement by the Centers for Disease Control and Prevention or the National Institute for Occupational Safety and Health.Address correspondence to Aaron J. Bird, M/S 3030, Exposure Assessment Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, 1095 Willowdale Road, Morgantown, West Virginia 26505, USA. E-mail: ABird@cdc.gov was observed to be very good for smaller particles, but less so for larger particles.

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