Applications and limitations of air dispersion modeling in environmental epidemiology

In epidemiological investigations, when the estimation of integrated exposures over long time intervals covering years or decades is required, the quantitative assignment of exposure levels by simplistic models may prove to be inadequate for most applications. This difficulty may be partially addressed by modifying the mathematical models used for the prediction of dispersions of emissions from pollution sources. A theoretical model based on the atmospheric dispersion of contaminants is proposed. While the development of the theoretical model is straightforward, the data requirements in the application of the model may impose some limitations. The methods developed to resolve or alleviate these limitations suggest that many currently used environmental exposure assignment techniques may be too crude to be of value; even the more sophisticated method proposed can only be used with some reservations. Although several difficulties associated with environmental exposure estimation remain unresolved, the careful and rigorous analysis of the available data and the application of the method suggested here can reduce the exposure misclassification errors to acceptable levels. The quantitative estimations of the limitations are based on estimation procedures and aerometric data used in a hilly terrain, and thus should represent testing of the method under an extreme condition.