Before the U.S. Environmental Protection Agency issued its 1986 'Guidelines for Estimating Exposures', it published proposed guidelines in the 'Federal Register' for public review and comment. The guidelines are intended to give risk analysts a basic framework and the tools they need to conduct human and nonhuman exposure assessments for specific pollutants. Four areas requiring further research were identified during the review process. One of the areas identified was the selection criteria for mathematical models used in exposure assessments. This document presents criteria for selecting the most appropriate mathematical model(s) to use in an exposure assessment related to air contamination. Part I contains general guidelines and principles for model selection and a step-by-step approach to identifying the appropriate model(s) to use in a specific application. Part II presents assumptions, limitations, and uncertainties associated with Gaussian plume models; discusses dispersion coefficients typically used in Gaussian models; and provides typical source parameters for hazardous waste management facilities. Part III characterizes indoor sources of emissions; describes the general mass-balance equation for indoor air quality, which incorporates the five major determinants of indoor pollutant levels; and discusses how dispersion models can be applied to model indoor air concentrations.

"March 1993." "EPA/600-8-91-038." "Richard Walentowicz ... served as project officer." Includes bibliographical references.