Janssen Larry, Luinenburg Michael D, Mullins Haskell E, Danisch Susan G, Nelson Thomas J
3M Occupational Health and Environmental Safety Division, Building 0235-02-E-91, St. Paul, MN 55144-1000, USA.
AIHA J (Fairfax, Va). 2003 Jul-Aug;64(4):480-6. doi: 10.1202/477.1.
A method for performing quantitative fit tests (QNFT) with N95 filtering facepiece respirators was developed by earlier investigators. The method employs a simple clamping device to allow the penetration of submicron aerosols through N95 filter media to be measured. The measured value is subtracted from total penetration, with the assumption that the remaining penetration represents faceseal leakage. The developers have used the clamp to assess respirator performance. This study evaluated the clamp's ability to measure filter penetration and determine fit factors. In Phase 1, subjects were quantitatively fit-tested with elastomeric half-facepiece respirators using both generated and ambient aerosols. QNFT were done with each aerosol with both P100 and N95 filters without disturbing the facepiece. In Phase 2 of the study elastomeric half facepieces were sealed to subjects' faces to eliminate faceseal leakage. Ambient aerosol QNFT were performed with P100 and N95 filters without disturbing the facepiece. In both phases the clamp was used to measure N95 filter penetration, which was then subtracted from total penetration for the N95 QNFT. It was hypothesized that N95 fit factors corrected for filter penetration would equal the P100 fit factors. Mean corrected N95 fit factors were significantly different from the P100 fit factors in each phase of the study. In addition, there was essentially no correlation between corrected N95 fit factors and P100 fit factors. It was concluded that the clamp method should not be used to fit-test N95 filtering facepieces or otherwise assess respirator performance.
早期研究人员开发了一种使用N95过滤式面罩呼吸器进行定量适合性测试（QNFT）的方法。该方法采用一种简单的夹紧装置，以测量亚微米气溶胶透过N95过滤介质的渗透率。测量值从总渗透率中减去，假定剩余的渗透率代表面罩密封泄漏。开发者已使用该夹具评估呼吸器性能。本研究评估了该夹具测量过滤器渗透率和确定适合因数的能力。在第1阶段，使用生成的气溶胶和环境气溶胶对受试者进行了弹性体半面罩呼吸器的定量适合性测试。在不干扰面罩的情况下，使用P100和N95过滤器对每种气溶胶进行QNFT。在研究的第2阶段，将弹性体半面罩密封在受试者面部，以消除面罩密封泄漏。在不干扰面罩的情况下，使用P100和N95过滤器进行环境气溶胶QNFT。在两个阶段中，均使用该夹具测量N95过滤器渗透率，然后从N95 QNFT的总渗透率中减去该值。研究假设，针对过滤器渗透率校正后的N95适合因数将等于P100适合因数。在研究的每个阶段，校正后的N95适合因数与P100适合因数均存在显著差异。此外，校正后的N95适合因数与P100适合因数之间基本没有相关性。研究得出结论，夹具法不应被用于N95过滤式面罩的适合性测试或以其他方式评估呼吸器性能。
