Human health risk in urban areas depends on multiple environmental features. We performeda year-round survey in a highly urbanized district located in temperate Argentina (GeneralSan Martín, Buenos Aires) to establish quality baseline information about environmentalhazards associated with health risk. Sampling was stratified in low and high hazardous zonesaccording to estimated indexes previously developed for the area for four hazards: drinkingwater and air pollution, and mosquito and rodent infestation. Water from wells showed lowerconcentrations of aluminum, manganese and iron, and higher values of arsenic than tapsamples, with records above the maximum permitted for arsenic, aluminum and chromium.Benzene concentration in air was higher in summer than in winter, and in areas close todumps and landfills, gas stations, high traffic pathways and industries with respect to lowhazard areas. Adult mosquito collections were more abundant in high hazardous areas, andpresented a seasonal pattern in which species of the genus Culex replaced themselves indifferent areas of the district. Rodent activity was recorded inside and outside dwellings, andits observed values did not differ between low and high hazardous areas. In the comparisonbetween field data and estimated hazard maps high accuracy was obtained for air pollutionmaps, intermediate accuracy for water pollution and mosquito infestation, and poor accuracyfor rodent infestation. How to improve field surveys and estimated maps are both discussed,highlighting the need for dynamic feedback between GIS-based models and environmentalmonitoring.