摘要:個人防護衣是用來保護工作人員避免有害物質經由皮膚暴露。截至目前為止雖然有許多方法來可用來測試防護衣的防護性能,然而均著重於防護液體噴濺以及蒸氣危害,對於空氣中粒狀污染物的防護性能卻尚無一套成熟並廣為使用的測試規範。在不同的工作環境中,正確選擇防護衣可以帶來最適當的防護效果,過當及不足的防護皆會造成危害,應力求避免。因此,本研究最主要的目的是發展三種測試方法來評估防護衣對微粒的防護性能,三種方法依序為:(1)主動抽氣過濾法:研究在超低過濾表面風速下,防護衣對微粒的過濾狀況;(2) 內循環採樣法:利用內循環系統來進行微粒採樣,評估防護衣微粒防護性能;(3)螢光微粒測試法:以螢光微粒評估防護衣微粒防護性能。不論是用在醫療照護者或是工業上所使用的各式各樣防護衣皆必須經過微粒過濾效率及阻抗測試。由於聚氨酯海綿具有容易清洗、可重複使用、容易控制各項物理特性等優點,可減低濾材之間的變異,進而能產生更優質的實驗數據,故本研究將以聚氨酯海綿作為實驗的參考濾材。至於各式微粒防護衣與其材質之技術資料,將由不同管道取得,已經接洽紡織綜合研究所與勞委會勞工安全衛生研究所,達成合作協議。研究採用定量輸出霧化器與超音波霧化噴嘴分別產生次微米級與微米級多粒徑分佈測試微粒。由於需要較高濃度的單一粒徑測試微粒,將以凝結核氣膠產生器(Condensation Monodisperse Aerosol Generator, CMAG, Model 3475, TSI Inc., St. Paul, MN) 產生。微粒產生後經過氣膠電性中和器(Am-241)以中和微粒帶電,使其達到波茲曼電量平衡的狀態。微粒量測儀器則是以氣動微粒分徑器(Aerodynamic Particle Sizer, APS, Model 3321, TSI Inc., St. Paul, MN, U.S.A.)量測粒徑大於0.7微米的微粒粒徑分佈;以電移動度掃描分徑器(Scanning Mobility Particle Sizer, SMPS, Model 3934, TSI Inc., St. Paul, MN, U.S.A.)量測小於0.7微米的微粒粒徑分佈。另外,以白光氣膠分徑儀 (White Light Aerosol Spectrometer, WELAS, Model 3000, PALAS, Greschbachstrasse 3 b, 76229 Karlsruhe, Germany) 量測0.1~20微米的微粒粒徑分佈,用來檢驗APS與部分SMPS的實驗數據力保正確性。主動抽氣過濾法中,過濾風速設定範圍涵蓋0.01~20 cm/s。極低過濾風速將利用大面積的濾材握持器及低抽氣流量來達成。實驗亦將改變濾材的擺放方向,探討氣流與濾材表面的夾角對過濾造成的效應。內循環採樣法中,循環的流率、採樣系統配置以及環境風速是最重要的實驗參數。螢光微粒測試法將利用分光光度計(UV-Visible Recording Spectrophotometer, Model UV-160A, Shimadzu, Japan) 來計算不同微粒粒徑的穿透率。若此國際合作計畫通過並順利執行,依照三種測試方法所得的實驗結果將與現行美國職業安全衛生研究所(NIOSH)刻正進行中的微粒磁性採樣法進行比較。透過比較或方法的整合,最終將訂定出最佳的微粒防護衣測試方法。
Abstract: Personal protective clothing is designed to protect workers against hazardous substances that might come into contact with the skin. Several widely accepted test methods are available to measure barrier properties of protective clothing against liquid and vapor assaults, but there is no officially accepted test method for particulate protective clothing. For any given situation, equipment and clothing should be selected that provide an adequate level of protection. Overprotection as well as under-protection can be hazardous and should be avoided. Accordingly, the main objective of this study is to develop three test methods for evaluating the performance of particulate protective clothing (PPC): (1) Active sampling method: study on aerosol penetration through PPC under extremely low filtration velocity, (2) Close-cycle sampling train method: development of a close cycle sampling train for evaluating PPC performance, (3) Fluorescent aerosol method: using fluorescent aerosols to measure aerosol penetration through protective ensembles.In the present study, a variety of protective garments, currently used in health care industry, will be tested for aerosol penetration and air resistance. Polyurethane foam filter will be used as the reference filter media for their cleanability and reusability. These unique features should reduce variability and lead to good quality experimental data. A variety of particulate protective ensembles and their technical information will be acquired from local and international suppliers and the Taiwan Textile research Institute. In order to cover a broad size range, a constant output atomizer and an ultrasonic atomizing nozzle will be used to generate polydisperse submicrometer-sized and micrometer-sized particles, respectively. Whenever high concentration monodisperse challenge aerosols are needed, a condensation nucleation aerosol generator will be used. The aerosol output will be neutralized by using a 25 mCi radioactive source, Am-241, and then introduced into the mixing and test chamber. Two different particle size spectrometers will be used to measure the aerosol concentrations and size distributions upstream and downstream of the filters: a scanning mobility particle sizer (SMPS) for particles smaller than 0.7 μm, and an aerodynamic particle sizer (APS) for particles larger than 0.7 μm. The third aerosol instrument, a Welas 3000 size spectrometer or equivalent, covering size range from 0.1 to 20 μm, will be used to double-check the aerosol penetration measurements by APS and SMPS.For active sampling method, filtration velocities ranging from 0.01 to 20 cm/sec will be used to study the flow dependency. This extremely low face velocity will be made possible by using a large filter hold and the lowest sampling flow feasible. The effect of filter orientation on the filter penetration will also be investigated by rotating the filter holder to be either parallel or perpendicular to the flow. The close-cycle sampling train method needs to be conducted in a wind tunnel-like chamber. The flow rate of the close-cycle system, the configuration of the sampling train, and the external approaching velocity will be the principal operating parameters. The fluorescent aerosol method will share the same test apparatus with the close-cycle sampling train method, except the challenge aerosols. A fluorescence meter will be used to measure the aerosol penetration through protective ensembles as a function of particle size.If the proposed international collaboration project is approved, the results of these three test methods will compare with the data of an on-going NIOSH project “magnetic passive aerosol sampler method” for evaluating aerosol penetration through PPC. The best test method or the combination of test methods under different operation conditions will be identified.