Currently available toxic vapor dispersion models at Air Force facilities do not adequately include the effects of structures on the rate of dispersion. Some relevant models and data sets are available in the literature as a result of research by other organizations. The literature will be reviewed and an assessment made of the feasibility of producing a viable modeling system and whether the effects of structures are likely to be significant relative to overall dispersion model uncertainty. The microcomputer based modeling system will account for aerodynamic effects around one building or groups of structures, including downwash and vapor trapping. Both neutrally-buoyant and dense gas cases will be considered, and the model will be constructured such that it is capable of a smooth transition to other dispersion models at downwind distances where the effects of the structures become insignificant.
