Housing characteristics and practices that potentially contribute to air pollution in Cali, Colombia. Background In Cali, Colombia, a group of children living in one of the poorest sectors of the city is being followed to determine the effects of environmental pollution on their health. Indoor air levels evaluation resulted in high levels of particulate matter, in addition to the presence of heavy metals in the air. This second phase seeks for potential sources of air pollution inside the house, taking into account housing characteristics and practices of its inhabitants. Methods A survey was applied to determine housing characteristics and practices that may have influence on indoor air quality. The survey was administered to mothers of a cohort of children who have been followed from the first trimester of pregnancy. Observation was also done in the home to determine the presence of dust and building materials. Results The 54.23% of households had over 15 years of built. Regarding the characteristics of ventilation 85.71% of households had window in their halls-dinning room facing the road, 38.18% of rooms had this characteristic. The latter is related to the report of vehicle traffic on the street often (27.12%). The research for practices like using candles, incense and mosquito coils was very low and at such times the frequency was "occasionally". Use of insecticides in the home was very frequent reaching 56.73% of households, where presentations that were tipically used was powder, liquid or aerosol. Discussion Indoor air quality has been poorly studied in Latin America, particularly in Colombia these studies are almost nonexistent. Given the differences in customs and housing characteristics with the developed countries, it is necessary to make an inventory of these conditions that may affect exposure to air pollution in vulnerable populations, with the aim of perform the actions necessary and feasible to improve the conditions of life of these populations.