###### Abstract  
The intense development in the remote sensing measurement techniques has contributed to establishing many spatial databases containing information on the terrain elevation and land cover, among others. Many resources of this type are made available for non-commercial applications by various organizations, e.g., by the United States Geological Survey (USGS) and the European Environment Agency (EEA). Special attention should be paid to the Digital Elevation Model data--Shuttle Radar Topography Mission (SRTM) [1] and the Digital Terrain's Cover data--Corine Land Cover raster data [2], which are characterized by high resolution (approximately 100 m). More precise models reflecting the topography and land cover are also available, however they cover only the territory of North America. The above-mentioned sets of spatial data constitute the necessary source of information for the advanced dispersion modeling system of air pollution. Furthermore, they enable calculations at a very high spatial resolution of 100 m. Increase in the number of computational receptors significantly prolongs the calculation time, especially in more advanced models. Thus, in the case of more complex simulations and for larger areas, there is a tendency to limit the number of receptors and thereby increase the grid spacing. The CALMET/CALPUFF modeling system (Exponent, Inc., Dallas, TX, USA) is more and more commonly used around the world in evaluations of the impact on air quality, including determination of shares of particular emission sources in shaping the level of air pollutant concentrations, especially in areas characterized by highly diversified landscape. A significant factor in this type of evaluations can be the method of description of the topography and land cover, as well as the resolution of the computational grid. The impact of topography on the modeling results of atmospheric dispersion using this model system was already noted (e.g., see [3; 4; 5]). In turn, the impact of the computational grid resolution on the air pollution modeling has been widely discussed thus far only for the mesoscale models with an extended description of chemical transformations in the atmosphere [6; 7; 8; 9; 10; 11; 12; 13; 14; 15]. The review of the literature indicates that, depending on the size of the calculation domain, a different resolution of grids is used in the CALMET/CALPUFF modeling system. In the case of the mesoscale calculations, a resolution of several or even a dozen or so kilometers is used [16; 17; 18; 19]; for the needs of air quality assessment in urban areas, a grid with the resolution of ca. 1 km is used [20; 21; 22; 23; 24; 25; 26; 27; 28]; and an analysis of the impact of single emission sources on air quality is usually conducted using finer computational grids with a spacing within the range of 100-500 m [4; 29; 30; 31; 32; 33; 34]. [PERSON] and [PERSON] [35] tested four grid resolutions (0.75, 1, 2 and 3 km) in the modeling domain of 100 km \(\times\) 100 km for open burning sources. In this case, it was concluded that the grid resolution of 1 km was the most appropriate resolution with regard to both accuracy of predicted data and acceptable computational time for the model simulation. Some experiments were also conducted, with the use of a marker, to assess the accuracy of the CALMET/CALPUFF model for high grid resolution (e.g., at 200 m and 400 m) [36; 37; 38]. The results of the accuracy assessment of the CALMET model in high-resolution grids indicate that this model correctly predicts the wind speed and direction at near field, but the 1-h averaging may be too long to reflect the actual conditions. The CALPUFF model is characterized by general underprediction of the results for a near field; in addition, it is characterized by good results for short and long range at a prolonged averaging time [37]. [PERSON] et al. [36] stated that the model returns good results in a near field and for a long averaging period in the case of calculations of deposition of the particulates.