Simulations are a common tool in the field of dispersion analysis of hazardous substances at the Swedish Defense Research Agency. An essential question to answer is which injury panorama to expect as a result of a given scenario. Existing effect models, for biological, chemical, and radioactive substances, require information regarding the exposure of the population in the area of interest. For simulation in urban areas, this requires, in turn, information regarding the positions of the population and the motion thereof. Modeling the motion of a population in a city is a complicated matter that requires detailed models as well as comprehensive data concerning the geometry of the city, infrastructure, demography and distribution of work places, residences, commercial shops etc. To meet this requirement, the motion of people has been analyzed at an individual level and implemented into a model called DUPS. DUPS is an acronym for Dynamic Urban Population Simulator and is used to populate an urban environment with synthetic agents traveling along individual path with different speeds serving the purpose of capturing the total exposure distribution among the entire population in a representative way.