The article is devoted to solving the scientific problem of decision support for the preventionand elimination of emergencies’ consequences based on solving the problem of structuring information.The relevance of this task is due to the need to develop theoretical foundations for optimizingthe risk of adverse effects on human health and the environment in connection with emergencies.The authors give definitions to the main terms of the studied subject area. A formalizedstatement of the problem to be solved is presented. A detailed emergencies’ classification with adescription of the presented classes’ features is given. The system of rules for decision support inemergencies should have a multi-level hierarchy, which allows for the construction of variousdecision-making trajectories on a top-down basis. The most suitable model for building such an informationspace is an ontological structure that provides the creation of the necessary multi-levelhierarchy, taking into account all the parameters and criteria that affect the development of the situation.The main elements of this ontological model are entities and relationships between them, thepresence of which at the upper level of decomposition will indicate the risk of an emergency, and ateach lower level it will expand the taxonomy of a detailed description of emergencies’ possible situationsand the necessary actions to prevent or eliminate them consequences. The processing of thisontological model of rules is implemented on the basis of the structuring information fuzzy methodproposed by the authors in emergencies, which differs from known analogs by the use of a new generalizedcriterion for optimizing the choice of decision support alternatives. The originality of theoptimization formulation of the structuring problem lies in the assessment of the information elementscontextual binding to a certain class of emergency situations, interdisciplinary, taking into accountthe presence of many links between subject areas, as well as taking into account the decrease in thelevel of information efficiency about the course of emergencies over time.