本研究主要測試在多階衝擊器內抑制微粒彈跳的相對溼度，而濕度控制是以 一個 Nafion 乾燥器達成的，利用相對溼度的升高以減少奈米微粒濃度高估現 象。為了確認此方法可應用於以後的現地或實驗室採樣，必須先了解微粒通過溼 度控制器之微粒損失與範圍。本研究結果得知通過溼度控制器後的微粒損失主要 為粗微粒，尤其大於5.6μm 以上之微粒，因此若要將溼度控制器與其它儀器搭配 使用來控制溼度，其儀器所收集的範圍必須不包含5.6μm 以上之微粒，才能保證 其準確性。
台灣大氣的相對溼度處於 50~100%下，鋁箔與鐵氟龍基質最常被當成 MOUDI 的衝擊基質，然而嚴重影響 MOUDI 收集微粒的準確性就屬微粒彈跳，
當相對溼度越低時微粒彈跳越明顯。實驗結果發現以未塗敷矽黃油的鋁箔基質收 集大氣微粒，奈米微粒在相對溼度 50%時會高估一倍以上，但相對溼度提升至 77%後，MOUDI 各階收集到的濃度卻與有塗敷的鋁箔基質相近，奈米微粒幾乎 無高估情形發生。若將相對溼度從 50%下降至 15%左右，其奈米微粒則會從高 估一倍變為兩倍左右，而粗微粒也會因為未塗敷基質無法有效捕捉而大量損失在 管壁上，因此若在低相對溼度且高粗微粒濃度地方使用MOUDI 採樣時必須校正 其損失量。
若以未塗敷的鐵氟龍當成MOUDI 內的收集基質，奈米微粒重量濃度在相對 溼度25%左右時將會高估 50%，但比起相對溼度在 52%且使用未塗敷鋁箔基質 所測得的奈米微粒濃度高估1.3 倍還要低上許多，這意味著在一般大氣溼度環境
箔收集效率相近，因此在高相對溼度條件下，MOUDI 的衝擊基質種類已無太大 影響奈米微粒的收集效率，使用未塗敷的鐵氟龍進行大氣採樣的相對溼度最佳操 作應為75%左右。
在高相對溼度的環境中，尤其是台灣山區，可直接使用未塗敷的鐵氟龍收集 大氣微粒以便於後續的化學分析；台灣的梅雨季相對溼度通常在70%以上，可使 用無塗敷的基質進行大氣採樣；但在相對溼度50~70%之間的地區，除非所收集 的微粒屬於液態則無重大影響，否則需使用溼度控制器將採樣口的相對溼度增加 至75%左右，且相對溼度不能超過 80%，以防止微粒粒徑分佈偏移。
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5 附錄
附錄一 使 M1、M4 各階鋁箔收集板均塗矽油時各階濃度差異比較, 980410 Dp50(μm) M1(μg/m3) M4(μg/m3) RSD(%)
>18 4.130 3.568 10.34 10~18 2.498 2.344 4.51 SUM 56.137 53.727
0.01 0.1 1 10 100
附錄二 使 M1、M4 各階鋁箔收集板均塗矽油時各階濃度差異比較, 980830 Dp50(μm) M1(μg/m3) M4(μg/m3) RSD(%)
>18 7.435 6.863 5.66 10~18 2.951 2.836 2.83 SUM 29.156 27.141
0.01 0.1 1 10 100
附錄三 使 M1、M4 各階鋁箔收集板均塗矽油時各階濃度差異比較, 981222 Dp50(μm) M1(μg/m3) M4(μg/m3) RSD(%)
>18 8.388 10.784 17.68 10~18 7.176 7.215 0.38 5.6~10 12.273 11.874 2.34 2.5~5.6 13.141 13.078 0.34 1.8~2.5 3.464 3.779 6.15 1.0~1.8 12.314 11.968 2.02 0.56~1.0 22.550 23.621 3.28 0.32~0.56 20.660 21.384 2.44 0.18~0.32 8.941 10.023 8.07
0.1~0.18 4.159 3.314 15.99
<0.1 2.796 2.944 3.65 SUM 115.862 119.983
0.01 0.1 1 10 100
Dpa, μm 0
20 40 60 80 100
d M /d lo g (D p a ), μ g/ m
3981222 M1 M4
MMAD
M1: 7.06 & 0.59 μm M4: 6.95 & 0.58 μm