Inherent safety has been recognized as a design approach useful to remove or
reduce hazards at the source instead of controlling them with add-on protective
barriers. Methods developed to date have largely been for the evaluating the safety
of a proposed design. At the moment it seems that the best practice is not adopted
quickly enough by the potential practitioners. The aim ofthis project is to develop a
toxicity model that can be used in the design stages of chemical producing plants to
predict the concentration at a given distance away from the point of release. The
scope ofthis project is to create a toxicity model for ammonia. The model consists
of two major parts, which are Gaussian Plume Equation and toxicity of ammonia.
The information on these two parts need to be merged so user(s) can then find out
the severity of the concentration of ammonia at a given distance away from the
point of incident. Using Microsoft Excel as the program to run this toxicity model,
the interface is arranged to make it as user-friendly as possible. Some of the
important parameters to be keyed into the model are molecular weight, density,
temperature, pressure, flow rate and distance of leak/rupture from ground level.
Overall, this project can be used to evaluate whether it is feasible for a chemical
producing plant to be built near housing areas. Further improvements are necessary to
commercialize and integrate this project with other riskeffects estimation
