Modelling aerosol processes related to the atmospheric dispersion of sarin

We have developed mathematical models for evaluating the atmospheric disper sion of selected chemical warfare agents (CWA), including the evaporation a nd settling of contaminant liquid droplets. The models and numerical result s presented may be utilised for designing protection and control measures a gainst the conceivable use of CWA's, The model AERCLOUD (AERosol CLOUD) was extended to treat two nerve agents, sarin and VX, and the mustard agent. T his model evaluates the thermodynamical evolution of a five-component aeros ol mixture, consisting of two-component droplets together with the surround ing three-component gas. We have performed numerical computations with this model on the evaporation and settling of airborne sarin droplets in charac teristic dispersal and atmospheric conditions. In particular, we have evalu ated the maximum radii (rm) of a totally evaporating droplet, in terms of t he ambient temperature and contaminant vapour concentration. The radii r(M) range from approximately 15-80 mum for sarin droplets for the selected amb ient conditions and initial heights. We have also evaluated deposition frac tions in terms of the initial droplet size. (C) 2001 Elsevier Science B.V. All rights reserved.