Efficiency of Sampling and Analysis of Asbestos Fibers on Filter Media: Implications for Exposure Assessment
Efficiency of Sampling and Analysis of Asbestos Fibers on Filter Media: Implications for Exposure Assessment
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过滤介质上石棉纤维的采样和分析效率：对暴露评估的影响
DOI：
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发表时间：
2008
影响因子：
2
通讯作者：
O. Crankshaw
中科院分区：
文献类型：
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作者：
D. Vallero;J. Kominsky;M. Beard;O. Crankshaw
为了测量空气中的石棉和其他纤维，空气样品必须代表纤维的实际数量和尺寸。通常，混合纤维素酯（MCE，0.45或0.8 μm孔径）和（在较小程度上）毛细孔聚碳酸酯（PC，0.4 μm孔径）膜过滤器用于收集气载石棉，以进行计数测量和纤维尺寸分析。在这项研究中，温石棉（纤维长度和长度均大于5 μm）是在气溶胶室中产生的，并通过直径为25 mm的MCE过滤介质取样，以比较0.45 μm孔径过滤器与0.8 μm孔径过滤器的纤维截留效率。此外，等离子体蚀刻时间对纤维密度的影响进行了评价。本研究表明，0.45 μm和0.8 μm孔径MCE过滤器对石棉气溶胶（结构长度大于或等于0.5 μm）的纤维截留效率存在显著差异。0.45 μm孔径MCE过滤器的纤维截留效率在统计学上显著高于0.8 μm孔径MCE过滤器。然而，对于长于5μm的石棉结构，0.45 μm和0.8 μm孔径MCE过滤器的纤维截留效率之间没有统计学显著差异。石棉纤维（≥ 0.5 μm）的平均密度随腐蚀时间的延长而增加。加倍的蚀刻时间增加了石棉过滤器负载在这项研究中的平均13%。等离子体蚀刻时间的长短对5 μm以上纤维的过滤负荷没有影响。许多石棉暴露风险模型将健康影响归因于长度超过5微米的纤维。在这些模型中，0.45 μm和0.8 μm孔径的MCE过滤器都可以对空气中的石棉浓度进行适当的估计。然而，一些模型表明，短于5 μm的石棉纤维的作用更为显著。这些模型的暴露监测应仅考虑美国环境保护署阿斯彭危害应急响应法案（AHERA）协议和其他方法推荐的0.45 μm孔径MCE过滤器。
To measure airborne asbestos and other fibers, an air sample must represent the actual number and size of fibers. Typically, mixed cellulose ester (MCE, 0.45 or 0.8 μm pore size) and, to a much lesser extent, capillary-pore polycarbonate (PC, 0.4 μm pore size) membrane filters are used to collect airborne asbestos for count measurement and fiber size analysis. In this research study, chrysotile asbestos (fibers both shorter and longer than 5 μm) were generated in an aerosol chamber and sampled by 25 mm diameter MCE filter media to compare the fiber retention efficiency of 0.45 μm pore size filters vs. 0.8 μm pore size filter media. In addition, the effect of plasma etching times on fiber densities was evaluated. This study demonstrated a significant difference in fiber retention efficiency between 0.45 μm and 0.8 μm pore size MCE filters for asbestos aerosols (structures longer than or equal to 0.5 μm length). The fiber retention efficiency of a 0.45 μm pore size MCE filter is statistically significantly higher than that of the 0.8 μm pore size MCE filter. However, for asbestos structures longer than 5μm, there is no statistically significant difference between the fiber retention efficiencies of the 0.45 μm and 0.8 μm pore size MCE filters. The mean density of asbestos fibers (longer than or equal to 0.5 μm) increased with etching time. Doubling the etching time increased the asbestos filter loading in this study by an average of 13%. The amount of plasma etching time had no effect on the filter loading for fibers longer than 5 μm. Many asbestos exposure risk models attribute health effects to fibers longer than 5 μm. In these models, both the 0.45 μm and 0.8 μm pore size MCE filter can produce suitable estimates of the airborne asbestos concentrations. However, some models suggest a more significant role for asbestos fibers shorter than 5 μm. Exposure monitoring for these models should consider only the 0.45 μm pore size MCE filters as recommended by the U.S. Environmental Protection Agency Asbestos Hazard Emergency Response Act (AHERA) protocol and other methods.