The most important characteristics of the automated information management systems for decision making support in emergency situations with the release of toxic substances are the accuracy and speed of the contamination zones modeling. In the scientific papers of the Russian scientists it is shown that at the initial stage of an emergency development there is a problem of incompleteness and inaccuracy of data on the emergency. In this regard, the topical tasks are to develop the methodologies and the algorithms implementing them that allow predicting and visualizing on the schematic map the maximum possible contamination zones with a minimum amount of the input data already at the initial stage of the accident.

Previously, the authors developed the methodologies and algorithmic support for predicting contamination zones in changing meteorological conditions during the release of accidentally chemically hazardous substances and harmful substances circulating in the Republic of Belarus.  The results of the creation of the express-method and algorithmic support for predicting maximum possible contamination zone depending on the key factors are presented in the article. These include: the time elapsed since the beginning of the emergency development, as well as the type, the quantity, and the thickness of the layer of harmful substances — liquefied gases.

Database was created for calculating the maximum possible zone of contamination with harmful substances, which is integrated into previously developed software. It allows predicting the maximum possible contamination zone with both accidentally chemically hazardous substances and harmful substances in any state of aggregation.