10.0 SUMMARY
        The atmospheric pathway component of the MEPAS model provides estimates of potential ambient air concentrations and deposition rates.  These outputs of the atmospheric pathway component are input to the MEPAS exposure assessment components.  The atmospheric and surface deposition concentrations are computed using standard Gaussian dispersion models that use local climatologic site data.  This computation accounts for influences such as the regional patterns of surface roughness and terrain heights.  Major removal and decay mechanisms are also incorporated.  This deposition computation provides estimates of both regional average and surface-specific contaminant deposition rates.  A complex-terrain option acounts for the influence of local nocturnal wind channeling near the source.