台灣為西太平洋邊緣的一個海島，與最近的中國大陸相距150多公里，過去研究結果顯示境外污染源對台灣酸沉降有重要的影響，在本研究中將討論境外污染源對台灣地面附近臭氧濃度的影響。 本研究採用CAMx模式進行模擬，氣象模式則採用RAMS模式，台灣地區污染源取自中鼎TEDS資料庫，境外污染源則取自Iowa大學。由過去的監測資料選擇一個高臭氧事件日和一個高PM10事件日進行分析探討。 由五月事件日發生時吹東南風，北部地區以及西北邊的海面上容易出現高濃度臭氧，境外污染物對臭氧濃度的影響主要在邊界附近，尤其是西北角和南部巴士海峽附近，如果沒有境外污染源台灣西北角的臭氧可以降低20ppb；十一月時吹東北風，較大影響的地區除邊界外還包括在高雄外海。至於氮氧化物的濃度受境外污染源影響較小。 Taiwan is an island located in the rim of West Pacific Ocean, apart from nearby Mainland China about 200Km. According to previous studies, transboundary pollutants have significant effects on the acid deposition in Taiwan. In this study, we will investigate the effects of transboundary pollutants on the ground-level ozone concentrations in Taiwan. The CAMx model was used for air quality simulations while RAMS was used to produce required meteorological input data. The emission data for Taiwan was obtained from TEDS. The emission data outside Taiwan was obtained from University of Iowa. Two episodes were selected for simulations from the air quality monitoring data of 2002. For the case of May episode, high ozone concentrations were occurred in the NW corner of Taiwan due to SE wind. The effects of transboundary pollutants on the ozone concentrations were noticeable in the boundaries of Taiwan, especially in the NW corner and southern Taiwan. If the emission sources outside Taiwan were omitted, the ozone concentration in NW Taiwan can reduce about 20ppb. For November episode, the areas significantly affected by transboundary pollutants include the boundaries of Taiwan and sea surface near Kaohsiung. The effects of transboundary pollutants on the NOx concentrations are unimportant.