This study compares the pulmonary function and prevalence of respiratory symptoms and disorders among school children living in smelter towns and other communities of Arizona. The rate of asthma was found to be significantly higher in whites than Mexican-Americans, although differences in related problems, such as wheezing, were not significant. When the subjects were grouped by area of residence, the children living in areas with relatively high particulate levels had significantly lower pulmonary function than children living in areas with low particulate levels. No relation between symptons or pulmonary function and sulfur dioxide levels observed.