A RATIONAL METHOD FOR SAMPLING AIRBORNE FIBROGENIC DUST

现有的呼吸性粉尘采样仪器高估了呼吸性粉尘的浓度， 吸入剂量超过400%，这取决于颗粒的大小分布。 空气中的尘埃 这种限制，加上分配的做法， 一个单一的RD值给任何给定的工作，无论水平 活动，即，呼吸频率（RF）和潮气量（TV）， 这与职业流行病学的进展不相符。 一种新的尘埃 将开发一种用于估计肺沉积（PD）的采样器， 缓解这些限制。 该设备由一个10 mm的旋风分离器组成 随后是单喷嘴一级冲击器。 尘埃部分 通过在10 mm直径显微镜上撞击收集感兴趣的物质 盖玻片 通过选择合适的空气，获得PD的估计 流量和直径的冲击，使综合性能将 模拟了不同RF和TV下的钟形PD曲线。 这 选择了一种配置，而不是两个串联的撞击器，因为 旋风分离器的收集效率与尖锐的截止曲线无关， 与冲击器相比，这导致与PD更好的匹配。 的 旋风除尘器也能够收集大量的灰尘， 超载 新采样器的性能将使用 单分散气溶胶范围为0.5微米至10微米，空气流速 在电池供电的个人采样的范围内，即，0.5-3.0 1/min。初步结果表明，将非常接近地估计PD 新的采样器。 该设备的优点包括： 各种工作负荷下肺沉积的近似值，改进 肺尘病流行病学研究中吸入剂量的估计， 并减少了化学分析的处理步骤，例如，银膜 过滤器可以用作二氧化硅粉尘的收集级，并且该过滤器 直接进行X射线衍射分析。 主要的限制 该设备的性能低估了< 0.5 μ m颗粒的PD，但净 由于这些因素的贡献很小， 颗粒（通常< 5%）占所收集样品的总重量。

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.