The concentration of ozone (O3), nitrogen oxides (NOx) and sulfur dioxide (SO2) in the atmosphere of Yakushima, a remote island of southern Japan, was measured in 2000-2001. Average concentrations of O3 were 29 and 43 ppbv at Seibu-Rindo (western area of Yakushima) and at Anbo (eastern area), respectively, in October 2000 and 49 and 46 ppbv at these areas, respectively, in February 2001 while average NOx concentrations were 2.2 and 2.8 ppbv at Seibu-Rindo and at Anbo, respectively, in October 2000 and 2.6 and 2.1 ppbv at these areas, respectively, in February 2001. No significant diurnal variation of O3 and NOx concentrations were found in both areas. Average concentrations of SO2 were 0.7 and 0.2 ppbv at Seibu-Rindo in October 2000 and at Anbo in February 2001, respectively, while a large increase of SO2 concentration (up to 11.0 and 12.5 ppbv) was recorded at Anbo in October 2000 and at Seibu-Rindo in February 2001, respectively, when air mass was derived from Kyushu Island by passing over Mt. Sakurajima (a volcano) in October 2000 and air mass coming from the Asian Continent / the Japan Islands in February 2001. THe data of air pollutant concentrations in Miyanoura (northern area of Yakushima), irregularly monitored by Kagoshima prefecture office, conbined with meteorological data in Kagoshima prefecture, suggested that O3 concentration would be higher (up to 60 ppbv) during fall to spring due to predominant northwest winds originating from the Asian Continent / the Japan Islands while, in other seasons, O3 concentrations would be lower due to predominant south winds originating from Pacific Ocean. Higher O3 concentrations during cold seasons could cause forest decline phenomena in Yakushima. SO2 were suggested to be transported from Mt. Sakurajima and from the region of the Asian Continent / the Japan Islands and its effect to forest plants needs to be evaluated by further monitoring
