In order to determine the most representative locations for measuring reliably varying concentrations of Total Suspended Particulates (TSP) in Santa Marta city, a field study was conducted. Emission and dispersion models were used in the urban area as well. Using the ‘Sphere of Influence’ method, the most representative areas in terms of TSP variation with relation to air quality were determined. The information collected in the field as well as the simulations do show clearly four different zones, where the TSP concentrations at a given station are representative, or can be extrapolated with a known confidence level. In order to measure and understand the variation in air quality, a monitoring station must be located in each area. This methodology is simple, produces reliable results that reduce the uncertainty concerning the location of air quality monitoring stations.