Abstract：
Filtering facepieces (FFP), mainly class FFP2 particle half masks (EN 149:2001#x02009;+ A1:2009), are commonly used in European mines to protect workers from respirable dust, especially from particulate matter (PM) with a diameter of 4 µm or less (PM4). The aerosol associated with diesel exhaust (DE) is dominated by submicrometer particles (with a diameter of less than 1 µm) and nanoparticles (size in the range between 10 and 500 nm). In the European Union (EU), the occupational exposure level (OEL) for DE has been defined in terms of elemental carbon (EC) concentration. Based on measurements in underground mines, on average, 60% of EC associated with PM4 was contained in PM with a diameter of 1 µm or less (PM1). Particle number size distribution (PNSD) of PM1 showed that the most numerous were particles in the size range of 20 to 300 nm. Four popular types of certified FFP2 half masks were tested for penetration. Brand new and thermally conditioned masks of each type were included in the study. NaCl aerosol in the particle size range of 7 to 270 nm was used for tests. Filtration efficiencies of 98.5% (median) or higher were achieved. Aerosol penetration was a function of particle size. Maximum penetration was observed between 20 and 60 nm, depending on the type of mask. During filtration, aerosol characteristics changed. Nanoparticles ranging in size from 7 to about 60 nm were removed to a very limited extent. The change was more noticeable for brand-new masks compared to the thermally conditioned ones. Usually, aerosol penetration through thermally conditioned masks was lower and more consistent. It was confirmed that the half masks of the FFP2 class are capable of filtering submicrometer aerosol in particle size range 7 to 270 nm with an efficiency exceeding 96% and can contribute to achieving compliance with the OEL for DE in the mining sector.
摘要：
过滤面罩(FFP),主要是FFP2类颗粒半面罩（EN149：2001+A1：2009）通常用于欧洲矿山，以保护工人免受可吸入粉尘的影响，特别是来自直径为4µm或更小的颗粒物（PM）（PM4）。与柴油机废气（DE）相关的气溶胶以亚微米颗粒（直径小于1μm）和纳米颗粒（尺寸在10至500nm之间）为主。在欧洲联盟(欧盟)，DE的职业暴露水平（OEL）已根据元素碳（EC）浓度定义。根据地下矿井的测量，平均而言,与PM4相关的EC的60％包含在直径为1µm或更小（PM1）的PM中。PM1的粒径分布（PNSD）表明，数量最多的是粒径范围为20-300nm的颗粒。测试了四种流行类型的经认证的FFP2半面罩的穿透性。研究中包括了每种类型的全新和热调节面罩。使用粒径范围为7-270nm的NaCl气溶胶进行测试。实现了98.5%(中值)或更高的过滤效率。气溶胶渗透是粒度的函数。在20和60nm之间观察到最大穿透，取决于面具的类型。在过滤过程中,气溶胶特性发生了变化。尺寸范围为7至约60nm的纳米颗粒被去除至非常有限的程度。与热调节面罩相比，全新面罩的变化更为明显。通常,通过热调节面罩的气溶胶渗透更低，更一致。已经证实，FFP2类的半面罩能够过滤粒径范围为7-270nm的亚微米气溶胶，效率超过96％，并且可以有助于实现采矿部门DE的OEL。
