可呼吸性氣膠分徑採樣器效能比較研究

Performance Comparison of Respirable Aerosol Size- Selective Samplers

新近研發之海綿分徑採樣器（foam sampler），除了在50 %截取粒徑（cut-off size）及斜率（slope）能精確的符合ACGIH/CEN/ISO新定義的呼吸沈積曲線外，相較於工業衛生領域常用之採樣器，海綿採樣器更具備有便宜、輕巧、採樣準確度高之㊝點。並能因應工作場所的採樣條件，而改變其採樣流量，以符合採樣標準。但仍須針對採樣器的精、準度與穩定性進行鑑定，因此，藉由與現有採樣器的比較，以確定海綿採樣器的㊝越性。實驗室驗證是利用一超音波霧化噴嘴，產生穩定濃度之液態酉太酸二辛酯（Dioctyl Phthalate, DOP）及固態酒石酸鉀鈉（Potassium Sodium Tartrate Tetrahydrate, PST）測試氣懸微粒。實驗中以氣動粒徑分析儀（Aerodynamic Particle Sizer, APS）進行氣懸微粒濃度與粒徑分布的測量。實驗結果顯示：氣懸微粒是呈液體狀或是粒徑較小的固體微粒時，海綿分徑採樣器具有較準確，同時也較精確的效能。但若是氣懸微粒是較大粒徑的固體微粒，則海綿採樣器呈現有較高的微粒彈跳，造成此粒徑範圍氣懸微粒之穿透率變異性增大。此結果顯示不同乾燥程度之氣懸微粒，與其撞擊表面之彈性係數以及微粒之負載累積均可能是造成此變異的因子。

The newly developed respirable aerosol sampler (Foam Sampler) has shown some advantages over other types of sampler. The superiority of using foams includes: (1) being the only sampler ever having the potential to match both the 50 % cut-off size and the slope of the conventions defined by the ISO, CEN, and ACGIH, (2) the versatility and flexibility to increase and/or decrease the sampling flow rate to meet the need in the workplace, and (3) the extra information (mass, chemical composition, etc.) of the aerosol particles collected on the foams. However, the Foam Sampler still need to pass the validation process, including both accuracy and precision tests. The performance comparisons with other types of sampler were conducted to confirm the advantages and the disadvantages as well. An ultrasonic atomizing nozzle was used to generate challenge liquid (Dioctyl Phthalate, DOP) or solid (Potassium sodium Tartrate Tetrahydrate, PST) aerosol particles of appropriate size distributions. The aerosol number concentrations upstream and downstream of the samplers were measured by using an Aerodynamic Particle Sizer (APS). The bias and precision of sampled masses were calculated for all three types of respirable dust sampler from measured penetration curves. These quantities were then combined to calculate the inaccuracy with respect to sampling conventions for respirable dust. The foam samplers tested were shown to have significant advantages in terms of sampling bias over other types of samplers currently in use for sampling respirable dust, when the workplace aerosols were liquid or small solid particles. The aerosol penetration through the foam samplers showed significant bounce-off (when the challenge aerosolsm in diamree stoerli)d, wanhdil ela trhgee ro tthaenr t5y pes of samplers experienced less bounce-off, but the penetration might fluctuate depending on the elastic properties of both the aerosols and the impaction surface.