A RATIONAL METHOD FOR SAMPLING AIRBONE FIBROGENIC DUST

目前的呼吸性粉尘采样仪器高估了 吸入剂量增加400%以上，具体取决于吸入物的大小分布 空气中的尘埃。这一限制，连同分配给 任何给定作业的RD的单一值，无论 活动量，即呼吸频率(Rf)和潮气量(Tv)是 与职业流行病学的进步格格不入。新的尘埃 用于估计肺沉积(PD)的取样器将被开发为 缓解这些限制。该装置由一个10毫米的旋风分离器组成 然后是单喷嘴单级冲击器。尘埃的分数 兴趣是通过撞击直径10毫米的显微镜收集的 封面纸条。通过选择适当的空气来获得PD的估计 冲击器的流量和直径，从而使综合性能 模拟了不同射频和电视下局部放电的钟形曲线。这 选择配置，而不是串联两个冲击器，因为 旋风收集效率与陡峭的截止曲线无关， 与冲击器相比，这导致了与PD更好的匹配。这个 气旋还能够收集大量的尘埃，而不是 超载。新采样器的性能将使用以下方法进行评估 在空气流速下，单分散气溶胶的范围从0.5um到10um 在电池供电的个人采样范围内，即0.5-3.0 1/分钟。初步结果表明，将非常密切地估计PD 被新的取样器。该装置的优点包括接近 改进了各种工作负荷下的肺沉积近似值 尘肺流行病学研究中的吸入剂量估算， 并且减少了用于化学分析的处理步骤，例如银膜 过滤器可用作二氧化硅粉尘的收集级，过滤器 直接提交进行X射线衍射分析。主要的局限性是 是低估了粒子&lt；0.5微米的Pd，但净 影响是微不足道的，因为这些贡献非常小 颗粒(通常为5%)占所收集样本的总重量。

Current sampling instruments of respirable dust (RD) overestimate the inhaled dose by more than 400%, depending on the size distribution of the airborne dust. This limitation, together with the practices of assigning a single value for RD to any given job, regardless of the level of activity, i.e., respiratory frequencies (RF) and tidal volumes (TV), are incompatible with the advances in occupational epidemiology. A new dust sampler designed to estimate pulmonary deposition (PD) will be developed to alleviate these limitations. The device consists of a 10 mm cyclone followed by a single-nozzle one-stage impactor. The dust fraction of interest is collected by impaction on a 10 mm diameter microscope coverslip. Estimation of PD is obtained by selecting the appropriate air flow rate and diameter of impactor, so that the combined performance would simulate the bellshaped curves of PD at various RF and TV. This configuration is selected, rather than two impactors in series, because cyclone collection efficiency is not associated with a sharp cut-off curve, as compared to an impactor, which results in better matching to PD. The cyclone is also capable of collecting large amounts of dust without overloading. Performance of the new sampler will be evaluated using monodispersed aerosols ranging from 0.5 um to 10 um at air flow rates within the range of battery-operated personal sampling, i.e., 0.5-3.0 1/min. Preliminary results indicate that PD will be estimated very closely by the new sampler. The advantages of the device include close approximation of pulmonary deposition at various work loads, improved estimation of the inhaled dose in epidemiologic studies of pneumoconiosis, and reduced handling steps for chemical analysis, e.g., a silver membrane filter may be used as the collection stage for silica dust, and the filter is directly submitted for x-ray diffraction analysis. The main limitation of the device is underestimation of PD for particles < 0.5 um, but the net effect is negligible because of the very small contribution of these particles (usually < 5%) to the total weight of the collected sample.