Mobile sources contribute directly or indirectly with most of the atmospheric emissions in Colombian cities. Quantification of mobile source emissions rely on emission factors (EF) and vehicle activity. Estimated EF before 2010 may not reflect the reduction of sulfur content in diesel and the renovation and deterioration of passenger vehicles, thus, emission levels may be over or under estimated. To account for these changes, the MOVES model in Bogota and obtained a new database of on-road vehicle emission factors was implemented. Local information of activity rates, speed profiles, vehicle population distribution and age, meteorology and fuel composition was used. Emissions were estimated with these new set of EF and compared with previous inventories. Large reductions in SO (-87%), CO (-65%), and VOC (-62%) emissions from mobiles sources and lower reductions in NO (-20%) were observed. Other pollutants, e.g., PM (+15%) and CO (+28%) reported increases. A new database of onroad vehicle emission factors for Bogota, which can be applied in other Colombian cities in the absence of local data, is provided. 2 x 2.5 2