Performance of an improperly sized and stretched-out loose-fitting powered air-purifying respirator: Manikin-based study
Performance of an improperly sized and stretched-out loose-fitting powered air-purifying respirator: Manikin-based study
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DOI：
10.1080/15459624.2015.1098780
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发表时间：
2016-03-03
影响因子：
2
通讯作者：
Grinshpun, Sergey A.
中科院分区：
文献类型：
--
作者：
Gao, Shuang;McKay, Roy T.;Grinshpun, Sergey A.
本研究的目的是调查一个动力空气净化呼吸器（PAPR）配备了一个不适当的大小或伸展出宽松的配合面罩使用恒定和循环流量条件下提供的保护水平。测试了两种型号的PAPR面罩尺寸不当以及拉伸面罩。这些面罩在两个版本中进行了检查：有排气孔和没有排气孔。将宽松的面罩（尺寸“大”）戴在小型人体模型头模上，并在暴露室中用氯化钠（NaCl）气溶胶颗粒进行挑战。使用机电呼吸记录和模拟系统（BRSS）应用平均吸气流量（MIFs）为30、55、85和135 L/min的四个循环流量。人体模型拟合系数（mFF）确定为面罩外部（C-out）与内部（C-in）气溶胶浓度的比值，使用P-Trak冷凝颗粒计数器（CPC）测量。结果表明，随着MIF的增加，mFF呈指数下降。拉伸面罩的emFF值明显低于未受损面罩的值。面罩类型和MIF被发现显着影响的性能宽松拟合PAPR。排气孔的效果不太明显，取决于面罩类型。得出的结论是，尺寸不合适的面罩可能会在高强度工作负荷下提供相对较低的保护（mFF < 250）。还在恒定吸入流量下进行了测试，以探索微粒-面罩相互作用的机制。循环流模式得到的结果与恒定流条件下测试松拟合PAPR时产生的数据一致。根据恒流状态下的测量结果计算的mFF的时间加权平均值能够预测循环流状态下的保护。研究结果表明，项目管理人员需要为员工配备适当大小的面罩，并从工作场所移除伸展的面罩。制造商应在其用户说明中强调适当尺寸的重要性。
The objective of this study was to investigate the protection level offered by a Powered Air-Purifying Respirator (PAPR) equipped with an improperly sized or stretched-out loose-fitting facepiece using constant and cyclic flow conditions. Improperly sized PAPR facepieces of two models as well as a stretched-out facepiece were tested. These facepieces were examined in two versions: with and without exhaust holes. Loose-fitting facepieces (size "large") were donned on a small manikin headform and challenged with sodium chloride (NaCl) aerosol particles in an exposure chamber. Four cyclic flows with mean inspiratory flows (MIFs) of 30, 55, 85, and 135 L/min were applied using an electromechanical Breathing Recording and Simulation System (BRSS). The manikin Fit Factor (mFF) was determined as the ratio of aerosol concentrations outside (C-out) to inside (C-in) of the facepiece, measured with a P-Trak condensation particle counter (CPC). Results showed that the mFF decreased exponentially with increasing MIF. ThemFF values of the stretched-out facepiece were significantly lower than those obtained for the undamaged ones. Facepiece type and MIF were found to significantly affect the performance of the loose-fitting PAPR. The effect of the exhaust holes was less pronounced and depended on the facepiece type. It was concluded that an improperly sized facepiece might potentially offer relatively low protection (mFF < 250) at high to strenuous workloads. The testing was also performed at a constant inhalation flow to explore the mechanism of the particle-facepiece interaction. Results obtained with cyclic flow pattern were consistent with the data generated when testing the loose-fitting PAPR under constant flow conditions. The time-weighted average values of mFF calculated from the measurements conducted under the constant flow regime were capable of predicting the protection under cyclic flow regime. The findings suggest that program administrators need to equip employees with properly sized facepieces and remove stretched-out ones from workplace. Manufacturers should emphasize the importance of proper sizing with their user instructions.