The effect of aerosol particle size on the performance of an N95 filtering facepiece respirator (FFR) and a surgical mask (SM) was evaluated under different breathing conditions, including breathing frequency and mean inspiratory flow (MIF) rate. The FFR and SM were sealed on a manikin headform and challenged with charge-equilibrated NaCl aerosol. Filter penetration (P filter) was determined as the ratio of aerosol concentrations inside and outside the FFR/SM size-selectively (28 channels) within a range of 20 to 500 nm. In addition, the same models of the FFR and SM were donned, but not sealed, on an advanced manikin headform covered with skin-like material. Total inward leakage (TIL), which represents the total particle penetration, was measured under conditions identical to the filter penetration experiment. Testing was conducted at four mean MIFs (15, 30, 55, and 85 L/min) combined with five breathing frequencies (10, 15, 20, 25, and 30 breaths/min). The results show that SM produced much higher P filter and TIL values, and thus provide little protection against aerosols in the size range tested. P filter was significantly affected by particle size and breathing flow rate (p < 0.05) for the tested FFR and SM. Surprisingly, for both devices, P filter as a function of the particle size exhibited more than one peak under all tested breathing conditions. The effect of breathing frequency on P filter was generally less pronounced, especially for lower MIFs. For the FFR and SM, TIL increased with increasing particle size up to about 50 nm; for particles above 50 nm, the total penetration was not significantly affected by particle size and breathing frequency; however, the effect of MIF remained significant. Copyright 2013 American Association for Aerosol Research

中文翻译：

---

不同呼吸条件下粒径对 N95 过滤式面罩呼吸器和外科口罩性能的影响

在不同呼吸条件下评估气溶胶粒径对 N95 过滤式面罩呼吸器 (FFR) 和外科口罩 (SM) 性能的影响，包括呼吸频率和平均吸气流量 (MIF) 速率。FFR 和 SM 被密封在人体模型头模上，并用电荷平衡的 NaCl 气溶胶进行挑战。过滤器渗透率（P 过滤器）被确定为 20 至 500 nm 范围内的 FFR/SM 尺寸选择性（28 个通道）内部和外部气溶胶浓度的比率。此外，FFR 和 SM 的相同模型被佩戴在覆盖有类皮肤材料的高级人体模型头模上，但没有密封。总向内泄漏 (TIL) 代表总颗粒渗透率，是在与过滤器渗透实验相同的条件下测量的。测试以四种平均 MIF（15、30、55 和 85 L/min）结合五种呼吸频率（10、15、20、25 和 30 次呼吸/分钟）进行。结果表明，SM 产生更高的 P 过滤值和 TIL 值，因此对测试尺寸范围内的气溶胶几乎没有提供保护。对于测试的 FFR 和 SM，P 过滤器显着受到颗粒尺寸和呼吸流速的影响 (p < 0.05)。令人惊讶的是，对于这两种设备，P 过滤器作为颗粒尺寸的函数在所有测试的呼吸条件下都表现出多个峰值。呼吸频率对 P 过滤器的影响通常不太明显，特别是对于较低的 MIF。对于 FFR 和 SM，TIL 随着颗粒尺寸增加至约 50 nm 而增加；对于50 nm以上的颗粒物，总穿透力不受颗粒物大小和呼吸频率的显着影响；然而，MIF 的效果仍然显着。版权所有 2013 美国气溶胶研究协会