Rengasamy Samy, Eimer Benjamin C
National Institute for Occupational Safety and Health/National Personal Protective Technology Laboratory, Technology Research Branch, Pittsburgh, PA 15236, USA.
Ann Occup Hyg. 2011 Apr;55(3):253-63. doi: 10.1093/annhyg/meq096. Epub 2011 Feb 3.
Nanoparticle (<100 nm size) exposure in workplaces is a major concern because of the potential impact on human health. National Institute for Occupational Safety and Health (NIOSH)-approved particulate respirators are recommended for protection against nanoparticles based on their filtration efficiency at sealed conditions. Concerns have been raised on the lack of information for face seal leakage of nanoparticles, compromising respiratory protection in workplaces. To address this issue, filter penetration and total inward leakage (TIL) through artificial leaks were measured for NIOSH-approved N95 and P100 and European certified Conformit'e Europe'en-marked FFP2 and FFP3 filtering facepiece respirator models sealed to a breathing manikin kept inside a closed chamber. Monodisperse sucrose aerosols (8-80 nm size) generated by electrospray or polydisperse NaCl aerosols (20-1000 nm size) produced by atomization were passed into the chamber. Filter penetration and TIL were measured at 20, 30, and 40 l min(-1) breathing flow rates. The most penetrating particle size (MPPS) was ∼50 nm and filter penetrations for 50 and 100 nm size particles were markedly higher than the penetrations for 8 and 400 nm size particles. Filter penetrations increased with increasing flow rates. With artificially introduced leaks, the TIL values for all size particles increased with increasing leak sizes. With relatively smaller size leaks, the TIL measured for 50 nm size particles was ∼2-fold higher than the values for 8 and 400 nm size particles indicating that the TIL for the most penetrating particles was higher than for smaller and larger size particles. The data indicate that higher concentration of nanoparticles could occur inside the breathing zone of respirators in workplaces where nanoparticles in the MPPS range are present, when leakage is minimal compared to filter penetration. The TIL/penetration ratios obtained for 400 nm size particles were larger than the ratios obtained for 50 nm size particles at the three different flow rates and leak sizes indicating that face seal leakage, not filter penetration, contributing to the TIL for larger size particles. Further studies on face seal leakage of nanoparticles for respirator users in workplaces are needed to better understand the respiratory protection against nanoparticle exposure.
由于纳米颗粒（尺寸小于100纳米）对人体健康可能产生影响，其在工作场所的暴露成为一个主要问题。基于在密封条件下的过滤效率，建议使用美国国家职业安全与健康研究所（NIOSH）批准的颗粒物呼吸器来防护纳米颗粒。人们对纳米颗粒面部密封泄漏信息的缺乏表示担忧，这会影响工作场所的呼吸防护。为解决这个问题，对NIOSH批准的N95和P100以及欧洲认证的符合欧洲标准（Conformit'e Europe'en）标记的FFP2和FFP3过滤式面罩呼吸器型号进行了测量，这些呼吸器密封在置于封闭舱室内的呼吸人体模型上，测量通过人工泄漏的过滤器穿透率和总向内泄漏率（TIL）。通过电喷雾产生的单分散蔗糖气溶胶（尺寸为8 - 80纳米）或通过雾化产生的多分散氯化钠气溶胶（尺寸为20 - 1000纳米）被通入舱室。在20、30和40升/分钟（-1）的呼吸流量下测量过滤器穿透率和TIL。最易穿透粒径（MPPS）约为50纳米，50纳米和100纳米尺寸颗粒的过滤器穿透率明显高于8纳米和400纳米尺寸颗粒的穿透率。过滤器穿透率随流量增加而增加。对于人工引入的泄漏，所有尺寸颗粒的TIL值随泄漏尺寸增加而增加。对于相对较小尺寸的泄漏，50纳米尺寸颗粒的TIL测量值比8纳米和400纳米尺寸颗粒的TIL值高约2倍，这表明最易穿透颗粒的TIL高于较小和较大尺寸颗粒的TIL。数据表明，在工作场所中，当泄漏与过滤器穿透率相比很小时，如果存在MPPS范围内的纳米颗粒，呼吸器呼吸区内可能会出现更高浓度的纳米颗粒。在三种不同的流量和泄漏尺寸下，400纳米尺寸颗粒的TIL/穿透率比值大于50纳米尺寸颗粒的比值，这表明对于较大尺寸颗粒，面部密封泄漏而非过滤器穿透对TIL有贡献。需要对工作场所呼吸器使用者的纳米颗粒面部密封泄漏进行进一步研究，以更好地了解针对纳米颗粒暴露的呼吸防护。
