Cubatao is located on the coast of Brazil 44 km from Sao Paulo. Its geography and wind patterns limit dispersion of air pollutants which result from heavy industrial activity within the city. New York University and EPA in collaboration with the University of Sao Paulo are conducting a study to attempt to establish exposure-response relationships of the impact of specific industrial effluents on respiratory function in school age children. During the 1988 school year, March-June, Aug-Nov, 600 six year old children, attending six different kindergarten schools, underwent monthly spirometry tests. Because the children live within a 500 m radius of their school, pollution monitors were located on each of the six schools. Particles were collected using dichotomous stacked filter units placed on 20 m towers to reduce the influence of dust from unpaved roads. Three sites are in the densely populated downtown area, one is on a newly developed outskirt area, and the last two are residential areas, far from industries. The yearly average thoracic aerosol mass concentration (PM10) is very high on all sites, ranging from 59+39 micrometer/cu m to 240+122 micrometer/cu m, the number of days with mean PM10 > 100 micrometer/cu m range from 27% to 98%.