In order to attain the 2010 target of reducing national greenhouse gases by 6% to the 1990 level, with reference to the Kyoto Protocol, the Government of Japan has planned and implemented some measures, as well as related policies. This paper discusses the possible impact of these measures on the nitrogen-oxide and sulfur-dioxide emissions from road vehicles in the Hiroshima Prefecture (ca. 3 million population). The number of road vehicles based on vehicle and fuel types in the Hiroshima Prefecture for 1990-2000 are presented, as well as projections for the years 2005 and 2010 using the Gompertz model. Three scenarios were developed to assess the emissions, referring to the possible achievement of related measures and policies as well as new vehicle technologies. Prediction results show that nitrogen-oxide emissions may be decreased from 14.7 kton in 1990 to 9.3 kton in 2010 if Japanese energy-policy and new vehicle developments are successfully implemented. If they are less successfully implemented, the emissions will decrease slightly to 14 kton, in which the decrease of emissions was mostly from gasoline vehicle. The emission of sulfur dioxide was projected to decrease from 1.2 kton in 1990 to within the range 0.45-0.49 kton by 2010, as a result of measures to reduce sulfur content in diesel oil. (C) 2004 Elsevier Ltd. All rights reserved.