National Institute for Occupational Safety and Health, NPPTL, 626 Cochrans Mill Road, Pittsburgh, PA 15236, USA.
J Occup Environ Hyg. 2012;9(8):517-23. doi: 10.1080/15459624.2012.695962.
The restorative forces of elasticized tethering devices on N95 filtering facepiece respirators (N95 FFR), that occur in response to the application of a load (applied force) during donning, create the requisite pressure to effectively seal the respirator against the face and prevent excessive inward migration of harmful elements. Many workers don and doff the same N95 FFR multiple times in the course of a single workday, yet little is known regarding the possible degradation of these restorative loads and, by implication, protection with multiple donnings. This laboratory pilot study evaluated the degradation in loads of tethering devices of three models of N95 FFRs subjected to the strain of five wear periods of 15 min interspersed with 15-min periods without wear. Data indicate that there were load degradations at each donning that differed significantly with the FFR model (p = <0.001), the greatest of which occurred with the first donning. The N95 FFR model with the lowest restorative loads was able to pass fit testing in a previous study, indicating that lower loads, perhaps coupled with FFR model-specific features, are sufficient to provide an adequate face/FFR interface seal. Tethering devices are importantly related to issues of comfort and protection afforded by N95 FFR and additional research is warranted.
弹性系绳装置对 N95 过滤式面罩（N95 FFR）的恢复力，是在佩戴过程中对负载（应用力）施加时产生的，它产生了有效密封面罩与面部的必要压力，并防止有害元素过度向内迁移。许多工人在一个工作日内多次佩戴和脱下相同的 N95 FFR，但对于这些恢复力负载的可能降解，以及多次佩戴的可能保护效果，知之甚少。这项实验室试点研究评估了三种 N95 FFR 模型的系绳装置负载在经受五个 15 分钟穿着周期和五个 15 分钟不穿周期的应变后的降解情况。数据表明，在每次佩戴时都存在负载降解，这与 FFR 模型有显著差异（p = <0.001），其中第一次佩戴时的降解最大。在之前的研究中，具有最低恢复力负载的 N95 FFR 模型能够通过 fit 测试，这表明较低的负载，也许加上 FFR 模型特定的特征，足以提供足够的面部/FFR 接口密封。系绳装置与 N95 FFR 的舒适性和提供的保护问题密切相关，因此需要进行更多的研究。
