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The Simplified Test Protocol, developed in our earlier studies for testing personal inhalable aerosol samplers, was evaluated in a specially designed small open-section, close-loop wind tunnel. The sampling efficiencies of three personal inhalable aerosol samplers (IOM, GSP, and Button Aerosol Sampler) were measured with 65 μm particles, using the Simplified Test Protocol at four inlet orientations to the wind ( 0, 90, 180 , and 270°). The results were compared with the data collected from other evaluation approaches. Analysis of variance (ANOVA) has shown that there is no statistically significant difference in the samplers’ performance when they are tested in the small and large wind tunnels following the Simplified Test Protocol and in the large wind tunnel following the conventional approach (samplers on a full-size human manikin). Thus, the Simplified Test Protocol has been shown to be suitable for the performance evaluation of personal inhalable aerosol samplers. The new wind tunnel facility was also found useful for handling very large particles, which is a considerable advantage over traditional wind tunnels. Our new wind tunnel was successfully used to measure the sampling efficiencies of the IOM, GSP, and Button Aerosol Sampler when challenged with particles of up to approximately 250 μm aerodynamic diameter at wind velocities of 50 and 100 cm s −1 . The data show that the sampling efficiency of the IOM sampler depends significantly on the wind velocity and is above 100% for particles of 165 and 241 μm mass median aerodynamic diameter. This dependence is not statistically significant for the GSP and Button Aerosol Sampler, whose sampling efficiencies are similar to each other and do not change with increasing test particle size at the indicated wind velocities. Also, the sampling efficiencies of the GSP and Button Aerosol Sampler closely follow the independent data obtained by using a breathing and rotating manikin at a wind velocity of 100 cm s −1 . The new wind tunnel design is expected to enhance the ability to extend the inhalable convention beyond 100 μm .

Traditional protocols for the performance evaluation of personal inhalable aerosol samplers utilize full-size manikins and large cross-section wind tunnels. Thus, these sampler evaluation procedures are complex, very costly, and time consuming. In addition, it is difficult to provide an adequately uniform wind velocity and aerosol concentration over large cross-section wind tunnels. A simplified test protocol, developed in our recent studies, is evaluated in this paper. The protocol is based on a three-dimensional rectangular simplified torso that simulates the dimensions of the human chest. This arrangement allows simultaneous measurement in four discrete orientations to the wind, thus providing useful orientation-dependent sampler information and possibly reducing the number of measurements needed. Sampling efficiencies of four personal inhalable aerosol samplers (the IOM, GSP, 37-mm closed-face cassette, and the button sampler) were measured using the simplified test protocol and the traditional approach for three particle sizes (7, 29, and 70 μ m) in four inlet orientations to the wind (0, 90, 180, and 270°) and two wind velocities (0.5 and 2.0 m s -1 ). It was found that when these samplers were mounted on the simplified torso versus the full-size manikin, the sampling efficiencies responded to changes in the sampling conditions in the same way regardless of whether the samplers were mounted on the simplified torso or the full-size manikin. Also, the sampling efficiencies were found not to be statistically different when the samplers were mounted on the simplified torso versus the full-size manikin. Thus, the simplified test protocol was shown to be suitable for the performance evaluation of personal inhalable aerosol samplers.

The presently available protocol for evaluating the performance of personal aerosol samplers according to the inhalable convention is difficult to satisfy as it requires a large cross-section wind tunnel. The present study was initiated to simplify and reduce the cost of the test method by mounting the test samplers on a small, stationary torso instead of a full-size rotating manikin. The simplified torso consisted of a rectangular three-dimensional body (33 cm wide, 21 cm deep, 21 cm high). Replicates of the personal inhalable aerosol sampler under consideration were attached in the center of each vertical face of the simplified torso representing the three principal sampling orientations (facing the wind, turned 90°, and turned 180° to the wind). When the samplers were mounted on a full-size manikin, the air flow in the vicinity of the manikin was found to depend on the sampler location, symmetry of the manikin, and position of the manikin’s arms. On the simplified torso, the magnitude and direction of the air flow near the samplers were found to be comparable to that of the manikin. When subjected to nearly monodisperse aerosol flows (particle size of 70 μm, wind velocity of 50 and 200 cm s-1), both methods yielded aerosol sampling efficiencies that were statistically not different at three major sampling orientations. The advantages of the simplified torso are that fewer measurements need to be made; a smaller, less expensive wind tunnel can be used for the testing; and interlaboratory variability of personal inhalable samplers’ performance may be decreased.

The airflow and particle-velocity patterns in the vicinity of a curved, porous sampling surface constituting the inlet of an aerosol sampler, have been determined by Laser-Doppler Velocimetry. The tests were performed on a personal aerosol sampler with a concave sampling surface, referred to as the “button” sampler. Measurements with the button sampler were conducted in a low-speed, open-circuit, horizontal wind tunnel using two types of monodisperse aerosols: 2 μm essentially inertialess propylene glycol particles (their trajectories represent the flow streamlines) and 44 μm inertial fly ash particles. The tests were performed at two free stream velocities (0.5 and 4 m/s) and two sampler orientations (facing the wind and facing downward at 90° to the wind). The sampling flow rate was 2 L/min. Sampling through the curved surface was conducted while the button sampler was freely suspended in the flow or while it was attached to a vertical stagnation plate simulating the human torso. The results in...

Performance of three devices used for the total enumeration of airborne spores-the Air-O-Cell sampling cassette, the Burkard personal volumetric air sampler, and the Button Aerosol Sampler--was evaluated under controlled laboratory conditions. The first two are glass-slide impactors; the third collects spores on a filter. The samplers were challenged with 0.44-5.10 microm polystyrene latex particles and five microorganisms of 0.84-3.07 microm mean aerodynamic diameter: Streptomyces albus, Bacillus subtilis, Cladosporium cladosporioides, Penicillium brevicompactum, and Penicillium melinii. An optical particle counter measured the particle concentrations upstream and downstream of each sampler, and thus determined the physical collection efficiency of the three samplers. Collection efficiency of the Button Aerosol Sampler was close to 100% for the entire particle size range studied. The cut-off size of each impactor was 2.3-2.4 microm. Acridine orange (with epifluorescent microscopy) and lactophenol cotton blue (with bright light microscopy) staining techniques were used for the microscopic enumeration of spores. No significant difference in microscopic counts was found (at the 95% significance level) when using these two techniques with the Button Aerosol Sampler filters. When the lactophenol cotton blue staining was used to compare total microbial counts yielded by all three samplers, the Button Sampler showed significantly higher counts for the smaller size microorganisms (B. subtilis and C. cladosporioides). For the larger microorganisms (P. brevicompactum and P. melinii) all three samplers yielded similar results. Uniformity of particle deposition on the collection surface was highest for the Button Aerosol Sampler due to the design of its inlet. Thus, the filter collection method used with the Button Aerosol Sampler is suitable and can be advantageous for the enumeration of total airborne spores.