Reponen Tiina, Lee Shu-An, Grinshpun Sergey A, Johnson Erik, McKay Roy
Department of Environmental Health, University of Cincinnati, PO Box 670056, Cincinnati, OH 45267-0056, USA.
Ann Occup Hyg. 2011 Apr;55(3):264-71. doi: 10.1093/annhyg/meq085. Epub 2010 Dec 20.
This study investigated particle-size-selective protection factors (PFs) of four models of N95 filtering facepiece respirators (FFRs) that passed and failed fit testing. Particle size ranges were representative of individual viruses and bacteria (aerodynamic diameter d(a) = 0.04-1.3 μm).
Standard respirator fit testing was followed by particle-size-selective measurement of PFs while subjects wore N95 FFRs in a test chamber. PF values obtained for all subjects were then compared to those obtained for the subjects who passed the fit testing.
Overall fit test passing rate for all four models of FFRs was 67%. Of these, 29% had PFs <10 (the Occupational Safety and Health Administration Assigned Protection Factor designated for this type of respirator). When only subjects that passed fit testing were included, PFs improved with 9% having values <10. On average, the PFs were 1.4 times (29.5/21.5) higher when only data for those who passed fit testing were included. The minimum PFs were consistently observed in the particle size range of 0.08-0.2 μm.
Overall PFs increased when subjects passed fit testing. The results support the value of fit testing but also show for the first time that PFs are dependent on particle size regardless of fit testing status.
本研究调查了通过和未通过适合性测试的四种型号N95过滤式面罩呼吸器（FFR）的粒径选择性防护因数（PF）。粒径范围代表了单个病毒和细菌（空气动力学直径d(a)=0.04 - 1.3μm）。
在标准呼吸器适合性测试之后，当受试者在测试舱内佩戴N95 FFR时，对PF进行粒径选择性测量。然后将所有受试者获得的PF值与通过适合性测试的受试者获得的PF值进行比较。
所有四种型号FFR的总体适合性测试通过率为67%。其中，29%的PF<10（职业安全与健康管理局为这类呼吸器指定的指定防护因数）。当仅纳入通过适合性测试的受试者时，PF有所改善，9%的值<10。仅纳入通过适合性测试者的数据时，PF平均高出1.4倍（29.5/21.5）。在0.08 - 0.2μm粒径范围内始终观察到最低PF。
当受试者通过适合性测试时，总体PF增加。结果支持适合性测试的价值，但也首次表明，无论适合性测试状态如何，PF都取决于粒径。
