In the article, results of the air-quality experiment in a Nowy Sącz area have been presented. The experiment combining both calculations and measurements was done in July 1993. Its goal was to assess the capability of the ,,box-model" method for simulation time-series of ozone and other pollutants in the lowest layer of the atmosphere. The numeric calculations' results were verified by the measurements from the airquality monitoring network. The model's prognostic capacity was assessed by the qualitative and quantitative data analysis. For analyzed episode, the error of calculated maximum ozone concentrations did not exceed ±22% of measured maximum values. The calculated daily-average ozone concentrations were 29% lower comparing to measured values. TI1c errors of calculations were most probably due to the errors in distribution of depth of the mixing layer, assumed for the calculations.