市售防塵口罩濾材對奈米微粒捕集效率研究

Collection of Nanoparticles by Commercial Respirator Filters

防塵口罩是目前廣被使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呼吸防護具，雖然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捕集效率，但是卻沒有足夠的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。其次，也探討濾材帶電量對於不同粒徑微粒的捕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與微粒粒徑之間的關係。此外，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 微粒的穿透率受濾材帶電量的影響並不明顯。市售防塵口罩，一般而言，以驗證合格的口罩比未經驗的口罩有較高的過濾品質。

Particulate respirators are widely used in workplace to protect workers against hazardous airborne particles. 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 limited. Therefore, the objective of this study is to investigate the filtration efficiency of nanoparticles penetrating through commercialized filtering facepieces. Furthermore, the effects of filter charges on filter efficiency and the most penetrating particle size were also studied. 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 disposable masks tested in this study rely heavily 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 values were not affected by the amount of filter charge. In general, certified masks performed better than those without certification.