Manikin-based performance evaluation of N95 filtering-facepiece respirators challenged with nanoparticles
Manikin-based performance evaluation of N95 filtering-facepiece respirators challenged with nanoparticles
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DOI：
10.1093/annhyg/mei058
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发表时间：
2006-04-01
影响因子：
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通讯作者：
Grinshpun, SA
中科院分区：
文献类型：
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作者：
Balazy, A;Toivola, M;Grinshpun, SA
保护人类呼吸系统免受纳米颗粒的影响正在成为职业卫生领域的一个新问题。与1-100 nm相似的颗粒相关的潜在不良健康影响可能大于亚微米或微米级颗粒。两种型号的N95半面罩过滤净化器对纳米级颗粒的性能进行了评估，在两个吸入流速，30和85升/分钟（-1），以下基于人体模型的协议。使用宽范围粒子谱仪测量面罩外部和内部的气溶胶浓度。根据NIOSH 42 CFR 84法规，氯化钠颗粒通常用于认证N系列蒸发器，用作挑战气溶胶。目标颗粒尺寸范围为10至600 nm，尽管标准认证测试是用类似于300 nm的颗粒进行的，这被认为是最具穿透力的尺寸。结果表明，纳米颗粒通过面密封N95呼吸器的渗透可能超过5%阈值，特别是在高呼吸流速下。因此，N95呼吸机可能并不总是为工人提供预期的呼吸保护。在类似于30-70 nm的粒径范围内观察到代表最差呼吸器保护条件的最高穿透值。基于理论模拟，我们得出结论，对于利用机械过滤器的过滤器，峰值穿透确实发生在类似于300 nm的颗粒直径处;然而，对于通常用于N95过滤器的预充电纤维过滤器，峰值向纳米尺寸偏移。这项研究证实，颗粒物的中和是评估呼吸器效率的关键因素。确定了两种型号和两种流速下呼吸器性能的变异性。分析表明，对于直径为20-100 nm的颗粒，渗透的变异系数范围为0.10 - 0.54。在85 l min（-1）下的性能测试证明纳米颗粒过度（> 5%）渗透的N95澄清器的分数高达9/10。在一个相对较小的（0.096 m（3））试验箱和一个较大的（24.3 m（3））步入式试验箱中获得的试验结果基本相同，因此，表明基于实验室的评价具有充分代表呼吸器现场性能的良好潜力。
Protection of the human respiratory system from exposure to nanoparticles is becoming an emerging issue in occupational hygiene. The potential adverse health effects associated with particles of similar to 1-100 nm are probably greater than submicron or micron-sized particles. The performance of two models of N95 half-facepiece-filtering respirators against nano-sized particles was evaluated at two inhalation flow rates, 30 and 85 l min(-1), following a manikin-based protocol. The aerosol concentration was measured outside and inside the facepiece using the Wide-Range Particle Spectrometer. Sodium chloride particles, conventionally used to certify N-series respirators under NIOSH 42 CFR 84 regulations, were utilized as the challenge aerosol. The targeted particle sizes ranged from 10 to 600 nm, although the standard certification tests are performed with particles of similar to 300 nm, which is assumed to be the most penetrating size. The results indicate that the nanoparticle penetration through a face-sealed N95 respirator may be in excess of the 5% threshold, particularly at high respiratory flow rates. Thus, N95 respirators may not always provide the expected respiratory protection for workers. The highest penetration values representing the poorest respirator protection conditions were observed in the particle diameter range of similar to 30-70 nm. Based on the theoretical simulation, we have concluded that for respirators utilizing mechanical filters, the peak penetration indeed occurs at the particle diameter of similar to 300 nm; however, for pre-charged fiber filters, which are commonly used for N95 respirators, the peak shifts toward nano-sizes. This study has confirmed that the neutralization of particles is a crucial element in evaluating the efficiency of a respirator. The variability of the respirator's performance was determined for both models and both flow rates. The analysis revealed that the coefficient of variation of the penetration ranged from 0.10 to 0.54 for particles of 20-100 nm in diameter. The fraction of N95 respirators for which the performance test at 85 l min(-1) demonstrated excessive (> 5%) penetration of nanoparticles was as high as 9/10. The test results obtained in a relatively small (0.096 m(3)) test chamber and in a large (24.3 m(3)) walk-in chamber were found essentially the same, thus, suggesting that laboratory-based evaluations have a good potential to adequately represent the respirator field performance.