Introduction. Currently, the risk assessment method is widely used at the facilities. This is true in determining the chemical hazards arising in the storage infrastructure and transport of chemically dangerous substances. The basis of risk assessment analysis of chemical hazard is forecasting of the consequences of chemical accidents and contamination areas.

Methods. As a result, it was revealed that the methods contain wrong assumptions. In particular, the actual area of chemically dangerous substance spill and its absorption into the underlying surface are not taken into account. These assumptions are proposed to be eliminated by use spreading and infiltration coefficient in the risk assessment method of chemical hazards. These coefficients are calculated on the basis of experiments to determine the area of the spill and the proportion of infiltration in the underlying surface of the main types of chemically dangerous substance. The spreading surface coefficient clarifies the main features that effect on evaporation time, the area of the spill and the thickness of the film of chemically dangerous substance spill on the underlying surface.

Results and discussion. Infiltration coefficient determines the amount of chemically dangerous sub­stance absorbed into the underlying surface. In addition, it is not taken into account in the secondary cloud formation of chemical contamination. The article presents the coefficients that are calculated for the main types of chemically dangerous substance and ways to obtain them. An assessment of the chemical hazard was carried out using an improved methodology in the Republic of Mordovia. The procedure is compared with other methods.

Conclusion. Calculations show that the proposed methodology for chemical risk assessment will allow more accurate forecasting. It is better to assess the risk of chemical hazards.