Jensen P A
U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Cincinnati, Ohio 45226-1998.
Am Ind Hyg Assoc J. 1995 Mar;56(3):272-9. doi: 10.1080/15428119591017114.
This study substituted sampling heads with smaller holes to collect small particles with the International PBI Surface Air System (SAS) battery-powered, bioaerosol air samplers, which have proved inefficient in collecting small airborne particles such as free bacteria (e.g., < 2 microns). An Andersen six-stage (6-STG) sampler was used simultaneously with two SAS samplers (SAS high flow [SAS-HF] and Compact SAS [SAS-C]) to sample indoor air in two office environments. Discrepancies were observed in the flow rate results obtained using the manufacturer's Pitot Validation Kit (PVK). Air sampling results suggested no significant difference in the concentration of bacteria and fungi collected among the four sampling heads using either sampler model in a small sample (n = 5) at either site. However, with an additional 15 samples at Site B (n = 5 + 15 = 20), three of the four sampling heads statistically undersampled the 6-STG and the other sampling head. The field data were variable (geometric standard deviation [GSD] = 1.25-1.94 for bacteria; GSD = 1.18-3.51 for fungi), but within ranges previously observed. The manufacturer increased particle collection efficiency by decreasing the hole size; however, this increase was only noticeable after many replicates. The PVK may be used as an accurate flow rate measurement device with the SAS-HF sampler, though the Pitot tube measures only centerline velocity pressure. Because of the 10% decrease in flow rate resulting from the pressure drop across the PVK, the equation in the manufacturer's literature for calculation of average velocities (VAVG) provides a reasonable estimate of flow rate through the SAS-C sampler.
本研究使用国际PBI表面空气系统（SAS）电池供电的生物气溶胶空气采样器，更换了带有较小孔的采样头，以收集小颗粒，该采样器在收集诸如游离细菌（例如，<2微米）等空气中的小颗粒方面已被证明效率低下。同时使用一个安德森六级（6 - STG）采样器和两个SAS采样器（SAS高流量[SAS - HF]和紧凑型SAS[SAS - C]）对两个办公环境中的室内空气进行采样。在使用制造商的皮托管验证套件（PVK）获得的流速结果中观察到差异。空气采样结果表明，在任一地点的小样本（n = 5）中，使用任一采样器模型的四个采样头所收集的细菌和真菌浓度没有显著差异。然而，在B地点增加了15个样本（n = 5 + 15 = 20）后，四个采样头中的三个在统计学上对6 - STG和另一个采样头进行了欠采样。现场数据是可变的（细菌的几何标准偏差[GSD] = 1.25 - 1.94；真菌的GSD = 1.18 - 3.51），但在先前观察到的范围内。制造商通过减小孔尺寸提高了颗粒收集效率；然而，这种增加只有在多次重复后才明显。PVK可以用作SAS - HF采样器的精确流速测量装置，尽管皮托管仅测量中心线速度压力。由于PVK两端的压力降导致流速降低10%，制造商文献中用于计算平均速度（VAVG）的公式提供了通过SAS - C采样器的流速的合理估计。
