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Laboratory evaluation of a personal aethalometer for assessing airborne carbon nanotube exposures.
Journal of Occupational and Environmental Hygiene ( IF 2 ) Pub Date : 2020-04-14 , DOI: 10.1080/15459624.2020.1740237
Patrick O'Shaughnessy 1 , Adrianne Stoltenberg 1 , Craig Holder 1 , Ralph Altmaier 1
Affiliation  

Aethalometers are direct-reading instruments primarily used for measuring black carbon (BC) concentrations in workplace and ambient atmospheres. Aethalometer BC measurements of carbon nanotubes (CNTs) were compared to measurements made by other methods when subjected to high (>30 µg/m3) and low (1–30 µg/m3) CNT aerosol concentrations representing worst-case and typical workplace concentrations, respectively. A laboratory-based system was developed to generate carbon black, as an example of a nearly pure carbon, micron-sized aerosol, and two forms of multi-walled carbon nanotubes (CNTs): small-diameter (<8 nm) and large-diameter (50–80 nm). High-concentration trials were conducted during which a scanning mobility particle sizer (SMPS) was used to track particle count concentrations over time. Relative to the behavior of the SMPS counts over time, aethalometer readings exhibited a downward drift, which is indicative of aethalometer response subjected to high BC loading on the receiving filter of the instrument. A post-sample mathematical method was applied that adequately corrected for the drift. Low-concentration trials, during which concentration drift did not occur, were conducted to test aethalometer accuracy. The average BC concentration during a trial was compared to elemental carbon (EC) concentration sampled with a quartz-fiber filter and quantified by NIOSH Method 5040. The CB and large-diameter CNT concentrations measured with the aethalometer produced slopes when regressed on EC that were not significantly different from unity, whereas the small-diameter CNTs were under-sampled by the aethalometer relative to EC. These results indicate that aethalometer response may drift when evaluating CNT exposure scenarios, such as cleaning and powder handling, that produce concentrations >30 µg/m3. However, aethalometer accuracy remains consistent over time when sampling general work zones in which CNT concentrations are expected to be <30 µg/m3. A calibration check of aethalometer response relative to EC measured with Method 5040 is recommended to ensure that the aethalometer readings are not under sampling CNT concentrations as occurred with one of the CNTs evaluated in this study.



中文翻译:

用于评估空气传播的碳纳米管暴露量的个人温度计的实验室评估。

湿度计是一种直接读取仪器,主要用于测量工作场所和周围大气中的黑碳(BC)浓度。在高(> 30 µg / m 3)和低(1–30 µg / m 3)的情况下,将碳纳米管(CNT)的酒精度计BC测量与其他方法进行的测量进行比较)CNT气溶胶浓度分别代表最坏情况和典型工作场所浓度。开发了一种基于实验室的系统来生成炭黑,例如近乎纯净的碳,微米级气溶胶和两种形式的多壁碳纳米管(CNT):小直径(<8 nm)和大直径碳纳米管。直径(50–80 nm)。进行了高浓度试验,在此期间,使用了扫描迁移率粒度仪(SMPS)来跟踪随时间变化的颗粒计数浓度。相对于SMPS计数随时间的变化,湿度计读数显示出向下漂移,这表示在仪器接收滤波器上承受高BC负载时,湿度计的响应。采用了一种采样后数学方法,可以对漂移进行充分校正。低浓度试验 在此期间未发生浓度漂移,以测试湿度计的准确性。将试验期间的平均BC浓度与通过石英纤维过滤器采样并通过NIOSH方法5040进行定量的元素碳(EC)浓度进行比较。当在EC上回归时,用酒精度计测量的CB和大直径CNT浓度会产生斜率,即与统一性没有显着差异,而小直径的CNTs相对于EC而言,是通过烟度计进行欠采样的。这些结果表明,当评估浓度大于30 µg / m的CNT暴露场景(例如清洁和粉末处理)时,测湿计的响应可能会漂移。将试验期间的平均BC浓度与通过石英纤维过滤器采样并通过NIOSH方法5040进行定量的元素碳(EC)浓度进行比较。当在EC上回归时,用酒精度计测量的CB和大直径CNT浓度会产生斜率,即与统一性没有显着差异,而相对于EC,小直径的CNTs则由烟度计进行了欠采样。这些结果表明,当评估浓度大于30 µg / m的CNT暴露场景(例如清洁和粉末处理)时,测湿计的响应可能会漂移。将试验期间的平均BC浓度与通过石英纤维过滤器采样并通过NIOSH方法5040进行定量的元素碳(EC)浓度进行比较。当在EC上回归时,用酒精度计测量的CB和大直径CNT浓度会产生斜率,即与统一性没有显着差异,而相对于EC,小直径的CNTs则由烟度计进行了欠采样。这些结果表明,当评估浓度大于30 µg / m的CNT暴露场景(例如清洁和粉末处理)时,测湿计的响应可能会漂移。相对于EC,小直径CNTs的测量是通过湿度计进行的。这些结果表明,当评估浓度大于30 µg / m的CNT暴露情况(例如清洁和粉末处理)时,测湿计的响应可能会漂移。相对于EC,小直径CNTs的测量是通过湿度计进行的。这些结果表明,当评估浓度大于30 µg / m的CNT暴露场景(例如清洁和粉末处理)时,测湿计的响应可能会漂移。3。但是,在对CNT浓度预计<30 µg / m 3的一般工作区域进行采样时,测湿仪的精度会随时间保持一致。建议使用方法5040对相对于EC的湿度计响应进行校准检查,以确保该湿度计读数不低于本研究中评估的一种CNT所采样的CNT浓度。

更新日期:2020-04-14
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