This article deals with the complex evaluation of a working environment. The aim of this paper is to find a mathematical model for a comprehensive risk assessment of a harvester operator. The developed model is based on the mutual evaluation of dependent and independent variables. The selected independent (explanatory) input variables of the model are the equivalent sound pressure level, peak sound pressure level, operative temperature, and mental stress. The selected dependent variable is the riskiness of the work, which we determined by means of heart rate variability evaluation. Based on the underlying measured data, we compiled a mathematical model that seems to be perspective. This model takes into account quantitative information on risk factors that can be determined by objectivization, as well as qualitative information on the health of the assessed person.