Road transport emissions have straightforward effects on air quality requirements, at local, regional and even global scales. Nowadays, almost all of motor vehicles use fossil fuels that, within their use, produce emissions of a same range of pollutants, although the amount and ratio are different according to the fuel, type of vehicle and combustion conditions. This fact is especially important in saturated roads, because vehicles caught in traffic jams are at the most polluting scenario, in comparison with regular use of a vehicle. Due to the importance of these emissions and trying to enforce legal specifications, technological improvements are installed on vehicles, which allow one to reduce emissions, as well as fuel consumption. These aspects are thought as the main issue in sustainable development in road transport around cities. The main aim of this work is to calculate and analyze contributions of the Atlantic Highway within Galicia, NW of Spain, to the road traffic pollution in the cities connected by it. The highway considered, covers more than 220 km from the NW to the SW of the region, and connects several major cities in Galicia. A standard methodology for estimation of road traffic was applied, based on EMEP/CORINAIR (Emission Inventory Guidebook 2007 Technical Report No. 16/2007. European Environment Agency EEA, 2007). To guarantee consistence and comparability of the results obtained, COPERT 4 (Computer Programme to Calculate Emissions from Road Traffic) was chosen. The pollutants considered were CO, NOx, NMVOC, SOx, NH3, GHG and particles, and the reference year is 2006. To assess the importance of highway emissions, it was necessary to calculate emissions from regular traffic in neighbouring areas. For comparison purposes, the present work focus on EMEP grid cells crossed by the highway. Cells are (49,14), (49,15), (49,16), (49,17), (50,13) and (50,14). Evaluation of EMEP cells