Marine traffic in Osaka bay is very intensified and much emission amounts of SO_x and NO_x from ships is released but there is no regulation about atmospheric pollutants emission from ships. In this paper, we investigate the emission amounts of SO_x, NO_x and HC from vehicle, factory and ships in Osaka bay area and estimate the influence of ship emission on the atmospheric pollutants concentration, using the mesoscale model to predict the wind fields and the concentration prediction model including the dry deposition and photochemical reaction model. In Osaka bay area, the emission amounts of SO_x and NO_x from ships were about 30% of the total emission amounts, respectively. Using these emission data, the atmospheric pollutants concentrations were simulated on a summer fine day when high oxidant concentrations were measured at several observatories and were compared with observed data. Though some differences were seen between the simulated and observed values, the diurnal variation agreed reasonably. Next, the numerical simulation was carried out except for ship emission amounts and estimated the influence of ship emission on the atmospheric pollutants concentrations. It was found that ship emission raised SO_2, NO_2 and NO concentration not only in shore area but also in 40km inland.
