In Brazil, increasing air pollution in urban areas has led to a rise in respiratory diseases among children and the elderly and has also been the main cause of hospital admissions. This study aims to evaluate the air pollution levels in Vitória, capital of Espírito Santo State, Brazil, in comparison to Brazilian legislation and recent World Health Organization (WHO) guidelines, analyzing the spatial distribution of asthma cases treated at local outpatient services. A descriptive epidemiological study was performed with daily records on air pollution and outpatient treatment for respiratory diseases from 2001 to 2003, for children under 6 years of age. A geographic information system (GIS) was used to identify asthma distribution in the municipality. Air pollution levels were relatively low when compared to the Brazilian legislation and WHO guidelines. Only mean PM10 and NO2 exceeded the annual quality standard. The three highest asthma outpatient treatment rates were observed in the districts of São José, Jabou, and Morro do Quadro.