相位差顯微鏡鏡檢方法是目前石綿作業環境空氣中分析應用最廣者，本研究根據我國環保署所公告之空氣類檢測方法「石綿工廠排放管道及其空氣中石綿檢測法」(NIEA A424.10T)，針對三家水泥石綿浪板工廠及六家剎車來令工廠測定其周界環境空氣中石綿濃度，共取得58個樣本，其中1個樣本因背景粉塵值過高而無法計數，一家工廠附近有毛紡織廠，其15個樣本之石綿濃度有高估現象，故有效樣本數總計42個，石綿濃度平均值為0.02 fiber/mL，下風處採樣位置的纖維濃度有較高的趨勢。樣本中有98%之鏡檢纖維密度未達建議方法中規定100~1300 fiber/mm2，故計數的相對偏差理論值較NIOSH 7400法0.11~0.13為高，顯示計數纖維的變異性較大，測定結果有較大誤差。本方法雖不能真正測得石綿工廠周界空氣中石綿濃度，但仍可作為石綿非職業暴露
的參考指標。 Phase contrast microscopy (PCM) is widely used to measure of asbestos concentration in the workplace. The objective of this study was to determine the airborne asbestos concentration in neighborhood of the asbestos-related factories by PCM. Nine factories, 3 asbestos cement and 6 brake, were investigated, and a total of 58 air samples were collected, in which 42 samples were valid with average concentration of 0.02f/mL. The results showed that the concentrations of asbestos fiber in downwind areas were seemingly higher than those of other collected areas, and were depended on the sampling time and atmospheric conditions. Ninety-eight percents of the valid samples in the asbestos fiber density didn’t meet the requirement of NIEAA424.10T code. The standard deviations of the counting precision were more than 0.11~0.13 which required by NIOSH 7400 code. Although the proposed procedure had higher variability in the fiber counting and could not precisely determine the concentration of airborne asbestos, it could be a preliminary method to assessment the asbestos fiber concentration on the non-occupational exposure.