The impact caused by motorways depends on many factors that can be assessed using environmental indicators. The processing of empirical data to obtain equations for detecting indicator changes as a function of the flow of cars was made using statistical data processing methods, i.e. correlation and regression analysis. The relationship between the parameters in order to select the type of regression equation was found with the help of single-factor linear and non-linear models and by performing a regression analysis. The best choice of equation has been determined using values of correlation coefficient R and square of correlation coefficient R2. The uncertainty of the calculations made with the model has been described by the confidence interval of the mean value (i.e. the regression curve), whereas for new measurements, the interval of the specific value of the indicators is used. The regression analysis of data used in the paper has made it possible to obtain an empirical equation that shows the effects of independent variables (number of vehicles) upon the noise volume and the amount of PM10, NOx emissions in the air.