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計畫名稱: 奈米微粒對帶電濾材之過濾特性研究
計畫編號: IOSH91-H307
出版年月: 2003/03
委辦機關: 勞安所
計畫主持人: 葉文裕
共同計畫主持人:
執行機構: 行政院勞工委員會勞工安全衛生研究所
中文摘要:
許多的研究均證明了懸浮微粒與心肺疾病等健康效應的相關性,在某一質量濃度值之下,雖然奈米粒徑微粒對於總質量的貢獻相對於較大粒徑微粒是很小的一部份,但是,如果以數目加權來看,奈米微粒卻是具有較大的濃度,而這很可能就是奈米微粒產生較大健康效應的主要原因,換句話說,若這樣的假設是正確的,則目前許多用於週界環境或是作業環境的粒狀物濃度標準如果以「質量濃度」來進行規範的話,在一些情況之下,很有可能會低估粒狀污染物對於人體健康的影響。
呼吸防護具是目前廣備用於作業場所中以保護作業人員免遭受有害粒狀污染物暴露的設備,目前大部分的濾淨式防塵口罩均是以過濾材作為捕集微粒的介質,雖然截至目前為止,已經有許多的研究顯示用於防塵口罩的濾材對於微米以及次微米粒徑範圍的微粒具有相當高的收集效率,然而卻沒有資料以說明其對於奈米微粒的捕集效果。
因此本研究的目的即在於探討市面上的防塵口罩對於奈米微粒的捕集效率。帶電濾材是目前最被廣為使過濾介質,該種濾材由於多了靜電作用力,因此可以在比較低的空氣阻抗下達到高度的捕集效率。然而,此種濾材不但是收集效率或是最易穿透粒徑均會隨著電電量的減少而改變,而這樣的變化在測試標準的制訂上必須加以考量。因此,在本研究中亦將探討濾材帶之電量對於微粒收集效率以及最易穿透粒徑的影響。
在研究中使用了超音波霧化器以及定流量輸出噴霧器兩種微粒產生器,並配合氣動粒徑分析儀以及掃瞄式電移動度分徑器以量測濾材之過濾效率。實驗中,為了去除濾材的帶電,因此將濾材浸泡於異丙醇中5 分鐘後取出,待其自然乾燥後分別將這些浸泡過以及未浸泡之濾材利用上述之系統以量測其對於粒徑10 nm 至10 μm 微粒之過濾特性。結果顯示濾材帶電是影響市售防塵口罩效率的一個重要因素,當濾材帶電減少後,不僅微粒穿透率增加而且最易穿透粒徑也從奈米粒徑範圍移到次微米粒徑,其中穿透率的變化又以粒徑10 nm 至5 μm 之間的微粒較為顯著,至於粒徑小於10 nm 或大於5 μm 微粒的貫穿率受濾材帶電量的影響並不明顯。市售防塵口罩之品質與價格差異大,一般而言,經過檢驗合格的口罩比未經檢驗的口罩有較高的過濾品質。

英文摘要:
Many studies have now shown the association between airborne particulate matter and cardiorespiratory ill health. It has been hypothesized that these effects may be due to the nanoparticles (>100 nm) comprising the largest number of particles, rather than the mass, which is principally determined by larger sized particles. In the theory therefore, if the ultrafine particle hypothesis is correct, mass based particulate matter standards both used in atmospheric or industrial environment may in some circumstances seriously misrepresent the oxicity of the pollutant. Particulate respirators are widely used in workplace to protect workers against hazardous airborne particles. The filter medium is the main functional component of a respirator for removing airborne particulate matter. Although there are lots of studies showed the filter media performed with high collection efficiency for collecting micrometer and submicrometer sized particles, the data for ultrafine particles is unavailable.
The objective of this study is to investigate the filtration efficiency of nanoparticles penetrating through commercialized filtering facepieces. Most filter media used today are made of electret material. By additional electrostatic mechanisms, high removal efficiency can be achieved without incurring large pressure drop. However, not only the efficiency but also the most penetrating size of these materials is changed, as the electric charge is reduced or eliminated. Thus, the uncertainty associated with the change of efficiency and he most penetrating particle size should be taken into consideration when proposing new test requirements. Therefore, the effects of filter charges on filter efficiency and the most penetrating particle size will also be studied in this study.
In this study, two aerosol generators: an ultrasonic atomizing nozzle and a constant output atomizer and two particle size spectrometers: an aerodynamic particle sizer (APS) and a scanning mobility particle sizer (SMPS) were used to conduct the filter performance testing. In order to eliminate the electrostatic charges, filters were dipped in isopropanol for 5 minutes and allowed to dry. Then, these dipped filters, along with controls of each filter type were tested to determine the aerosol penetrations in the size range of 10 nm to 10 μm.
The results showed that the disposiable masks tested in this study rely heavly on their electrostatic charge to provide adequate filter efficiencies. As the electrostatic charge on the fibers of each filter was reduced, the aerosol penetration values in the 10 nm to 5 μm size range increased considerably and the most penetrating particle size noticeably shifted from nanometer range to submicrometer particles. On the other hand, almost all particles with size less than 10 nm or larger than 5 μm were collected in the filters, and the penetration alues wouldn’t affect by the amount of filter charge. The quality and price of commercial disposiable masks varies with brands. In general, certified masks performed better than those without certification.
計畫報告連結:
資料庫分類: 勞安所、處理、氣膠、個人防護器具、體外實驗、風險認知與溝通、風險管理、吸入、環境奈米物質、大氣生態系統、報告、消費者、技術研究者、一般民眾、公共政策、工程/人造、工作場所
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網頁更新日期:2016/06/15