A system and method for providing hazardous incident decision support and training includes a user interface component that receives situation definition data, a hazard assessment component and a decision aid. Decision support advice and decision prompts are presented by the system in response to the situation definition interface and hazard assessment. The hazard assessment and expert advice of the system are updated with elapsed time. In another embodiment of the present invention, graphical user interfaces are provided to display a set of menu entries wherein individual menu entries represent a hazardous incident characteristic. The user may select one or more of the menu entries to create a situation definition. Such definitions may be used, for example, to identify a hazardous agent based upon user-inputted signs and symptoms data.