Duling Matthew G, Lawrence Robert B, Slaven James E, Coffey Christopher C
Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, Division of Respiratory Disease Studies, National Institute for Occupational Safety and Health, Morgantown, WV 26505-2888, USA.
J Occup Environ Hyg. 2007 Jun;4(6):420-31. doi: 10.1080/15459620701346925.
This study investigates two different methods (random effects model and 5th percentile) for determining the performance of three types of respiratory protective devices (elastomeric N95 respirators, N95 filtering-facepiece respirators, and surgical masks) during a simulated workplace test. This study recalculated the protection level of three types of respiratory protective devices using the random effects model, compared the two methods with each other and the APF of 10 for half-facepiece respirators, and determined the value of each of the fit test protocols in attaining the desired level of simulated workplace protection factor (SWPF). Twenty-five test subjects with varying face sizes tested 15 models of elastomeric N95 respirators, 15 models of N95 filtering-facepiece respirators, and 6 models of surgical masks. Simulated workplace testing was conducted using a TSI PORTACOUNT Plus model 8020 and consisted of a series of seven exercises. Six simulated workplace tests were performed with redonning of the respirator/mask occurring between each test. Each of the six tests produced an SWPF. To determine the level of protection provided by the respiratory protective devices, a 90% lower confidence limit for the simulated workplace protection factor (SWPF(LCL90%)) and the 5th percentile of simulated workplace protection factor were computed. The 5th percentile method values could be up to seven times higher than the SWPF(LCL90%) values. Without fit testing, all half-facepiece N95 respirators had a 5th percentile of 4.6 and an SWPF(LCL90%) value of 2.7. N95 filtering-facepiece respirators as a class had values of 3.3 and 2.0, respectively, whereas N95 elastomeric respirators had values of 7.3 and 4.6, respectively. Surgical masks did not provide any protection, with values of 1.2 and 1.4, respectively. Passing either the Bitrex, saccharin, or Companion fit test resulted in the respirators providing the expected level of protection with 5th percentiles greater than or equal to 10 except when passing the Bitrex test with N95 filtering-facepiece respirators, which resulted in a 5th percentile of only 7.9. No substantial difference was seen between the three fit tests. All of the SWPF(LCL90%) values after passing a fit test were less than 10. The random model method provides a more conservative estimate of the protection provided by a respirator because it takes into account both between- and within-wearer variability.
本研究调查了两种不同方法（随机效应模型和第5百分位数），用于确定三种类型呼吸防护设备（弹性体N95呼吸器、N95过滤式面罩呼吸器和外科口罩）在模拟工作场所测试中的性能。本研究使用随机效应模型重新计算了三种类型呼吸防护设备的防护水平，将这两种方法相互比较，并与半面罩呼吸器的10倍适用防护因数（APF）进行比较，确定了每种适合性测试方案在达到所需模拟工作场所防护因数（SWPF）水平方面的价值。25名面部尺寸各异的测试对象对15种型号的弹性体N95呼吸器、15种型号的N95过滤式面罩呼吸器和6种型号的外科口罩进行了测试。使用TSI PORTACOUNT Plus 8020型仪器进行模拟工作场所测试，测试由一系列七个练习组成。每次测试之间进行呼吸器/口罩的重新佩戴，共进行了六次模拟工作场所测试。六次测试中的每次都产生了一个SWPF。为了确定呼吸防护设备提供的防护水平，计算了模拟工作场所防护因数的90%置信下限（SWPF(LCL90%)）和模拟工作场所防护因数的第5百分位数。第5百分位数法的值可能比SWPF(LCL90%)的值高出多达七倍。未经适合性测试时，所有半面罩N95呼吸器的第5百分位数为4.6，SWPF(LCL90%)值为2.7。作为一个类别，N95过滤式面罩呼吸器的相应值分别为3.3和2.0，而N95弹性体呼吸器的相应值分别为7.3和4.6。外科口罩未提供任何防护，相应值分别为1.2和1.4。通过Bitrex、糖精或Companion适合性测试中的任何一项，都会使呼吸器提供预期的防护水平，第5百分位数大于或等于10，但N95过滤式面罩呼吸器通过Bitrex测试时除外，此时第5百分位数仅为7.9。三种适合性测试之间未观察到实质性差异。通过适合性测试后的所有SWPF(LCL90%)值均小于10。随机模型法对呼吸器提供的防护提供了更保守的估计，因为它考虑了佩戴者之间和佩戴者内部的变异性。
