大氣中的粒狀污染物(particulate matter, PM)，特別是氣動力徑小於1.0微米的微粒 (如柴油引擎所排放之廢氣)對於人類健康造成的負面影響已經由許多的流行病學及動物毒理研究證實，並被世界衛生組織的國際癌症研究中心列爲第一級的致癌物。然而這些次微米微粒在總質量貢獻的比例並不顯著。另一方面，文獻指出微粒的有效密度及構形是影響次微米微粒在呼吸道中的傳輸及沉降的重要關鍵。故微粒質量和有效密度的量測是極為重要且有助於進一步瞭解其與健康的關連性。 氣懸微粒質量分析儀(Aerosol Particle Mass Analyzer, APM)為較為新穎且廣泛應用的氣膠質量即時監測儀器，常以DMA-APM和APM-SMPS等串聯式系統來取得微粒的有效密度等特性。近年來隨著環境變遷與人類健康的議題逐漸受到重視，將APM應用於大氣環境微粒監測的相關研究日益增多。然而氣體的特性(如：氣體黏滯度和平均自由徑)卻可能隨著量測地點的不同而改變，意味著APM的操作性能可能受到環境因素的影響而有所差異。故本研究以空氣、二氧化碳與氧氣分別做為實驗的載流氣體，量測50 nm和100 nm標準微粒的質量，結果顯示黏滯度高於空氣14%的氧氣在APM的量測上有質量高估6~9%的現象，但無顯著的粒徑效應；而黏致度低於空氣25%的二氧化碳則有質量低估1~25%的情形，但有顯著的粒徑效應。且此趨勢與模擬之傳輸函數結果相符。顯示當黏滯度與標準狀態的差異過大時，將降低APM量測結果的可信度。另一方面，比較DMA-APM和APM-SMPS兩系統的量測結果後發現，以APM-SMPS系統量測實驗室產生之氣膠微粒的有效密度的偏差較DMA-APM系統大，但在環境量測的結果經後處理後是可信的。而使用DMA-APM系統所得之APM電壓分佈若有偏峰且尾部無峰肩存在時，建議需針對多粒徑效應造成的影響做校正或是改以更高的系統解析度的進行實驗，以獲得更為精確的質量量測值。 ;Airborne particulate matter (PM), especially for submicron particles (dp,a<1.0 μm), e.g. diesel emission particle (DEP), has already been classified as group 1 carcinogenic material by IARC as a result of positive associations with various adverse human health effects. However, several scientific studies have shown that submicron particles often contribute only part of the total mass. Moreover, the fact of particle effective density and morphology play a prominent role in particle transport in respiratory tract was announced by ICRP and NCRO. Therefore, the mass distribution and effective density measurements are important, which also critical aerosol properties for understanding their health impact and associations between. Aerosol Particle Mass Analyzer (APM) is a lately instrument for determining particle mass, as well as particle effective density which obtained by coupled system such as DMA-APM or APM-SMPS. Due to the binary interest of human health and climate change nowadays, a growing number of APM field studies were reported. However, the gas viscosity and the mean free path could vary with the environmental condition. This implies that the performance of APM might be varied with altitude. In this study, CO2 and O2 were selected as the carrier gas and compare to the case of air. Both of simulated and experimentally results show that mass of 50 and 100 nm of PSL particles shows that the peak voltage on transfer function shift with a trend of the relative Cc-μ value. Mass measured by CO2 was underestimated 1~25% and size effect was observed. While mass was overestimated 6~9% by O2 but without size effect. Comparison and detail optimize condition between DMA-APM and APM-SMPS systems were also investigate in this study. Based on experimental results, DMA-APM system is favorable to determine the effective density in lab scale studies. And a simple way to judge the necessary of multiple charge correction of APM measured data was proposed.
