AbstractAn expert panel examined the influence of complex terrain, industrial plant obstacles and thermal inhomogeneities on the dispersion of gaseous plumes or aerosols resulting from accidental releases of hazardous materials. Perturbations in transport and dispersion induced by such flow disturbances were estimated. The limitations and accuracies of current numerical and physical modeling techniques were examined. Finally, important unresolved questions concerning the estimation of transport of hazardous materials in the presence of realistic industrial building, storage and transportation environments were identified.