## Hamilton study: estimating exposure to ambient suspended particles

In the industrial city of Hamilton, Ontario, Canada, we recently carried out an epidemiological study of the effect of environmental factors on respiratory health in 3500 elementary school children. The level and size distribution of suspended particles in ambient air was measured from 24-h samples taken at 6-day intervals from a network of 29 hivol TSP samplers, and nine Andersen 2000 4-stage cascade impactors. Exposure was computed by generating a 3-dimensional response surface using a linear regression model of the form: TSP = (1 + E + N)/sup 2/, based on monthly geometrical mean data for all sites. From thismore »