## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**The Type of Concentration**} & \multirow{2}{*}{**Variant**} & \multirow{2}{*}{**Grid Resolution (m)**} & \multicolumn{4}{c}{**NO\({}_{2}\) Concentration (ug/m\({}^{3}\))**} \\ \cline{4-7}  & & & & **Min.** & **Max.** & **Average** & **Standard Deviation** \\ \hline \multirow{3}{*}{C\({}_{1,\text{max}}\)} & V1 & 100 & 0.61 & 167.0 & 9.8 & 9.1 \\  & V2 & 250 & 0.60 & 140.0 & 10.3 & 8.4 \\  & V3 & 500 & 0.84 & 133.1 & 11.1 & 9.3 \\  & V4 & 1000 & 0.80 & 60.4 & 10.4 & 7.0 \\ \hline \multirow{3}{*}{C\({}_{24,\text{max}}\)} & V1 & 100 & 0.046 & 11.33 & 1.04 & 0.81 \\  & V2 & 250 & 0.046 & 9.08 & 1.10 & 0.79 \\  & V3 & 500 & 0.066 & 8.62 & 1.29 & 0.93 \\  & V4 & 1000 & 0.070 & 7.83 & 1.19 & 0.76 \\ \hline \multirow{3}{*}{C\({}_{4}\)} & V1 & 100 & 0.0030 & 1.712 & 0.106 & 0.112 \\  & V2 & 250 & 0.0035 & 1.643 & 0.110 & 0.111 \\ \cline{1-1}  & V3 & 500 & 0.0054 & 1.263 & 0.125 & 0.123 \\ \cline{1-1}  & V4 & 1000 & 0.0052 & 0.896 & 0.111 & 0.100 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Summary of minimum, maximum, average and standard deviation values for the calculation results for different types of NO\({}_{2}\) air concentrations obtained in the examined computational grids (variants). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Type of**} & \multicolumn{2}{c}{**Differences between**} & \multicolumn{2}{c}{**Differences between**} & \multicolumn{2}{c}{**Differences between**} \\ \multicolumn{2}{c}{**Concentration**} & \multicolumn{2}{c}{**Minimum Values**} & \multicolumn{2}{c}{**Maximum Values**} & \multicolumn{2}{c}{**Average Values**} \\ \cline{2-10}  & **V1-V2** & **V1-V3** & **V1-V4** & **V1-V2** & **V1-V3** & **V1-V4** & **V1-V2** & **V1-V3** & **V1-V4** \\ \hline C\({}_{1,\text{max}}\) & 0.01 & \(-\)0.23 & \(-\)0.19 & 27.0 & 33.9 & 106.6 & \(-\)0.5 & \(-\)1.3 & \(-\)0.6 \\ C\({}_{24,\text{max}}\) & 0.000 & \(-\)0.020 & \(-\)0.024 & 2.25 & 2.71 & 3.50 & \(-\)0.06 & \(-\)0.25 & \(-\)0.15 \\ C\({}_{4}\) & \(-\)0.0005 & \(-\)0.0024 & \(-\)maximum was obtained, in the case of Variants V1 and V2, are located, respectively, at a distance of ca. 650, and 500 m northeast of the emission source. On the other hand, in the case of Variants V3 and V4, the highest values of maximum 1-h concentrations occurred at different times and with different weather conditions. These conditions for Variants V1 and V2 were, respectively, as follows: wind speed 0.70 and 0.68 m/s; atmospheric stability classes 3 and 2; temperature 269 and 280 K; and height of the mixing layer 149 and 134 m. They were observed at the receptors located, respectively, ca. 400 and 600 m to the west of the emission source, that is, in a completely different place than in the case of Variants V1 and V2. Therefore, the use of grids with the resolution of 100-250 m, enabled obtaining the maximum 1-h concentrations in a similar time and place, while the less dense computational grids (in the range of 500-1000 m) did not make it possible, because the maximum values in these grids occurred in other places and under different weather conditions. The highest values of the maximum daily concentrations in the case of Variants V1 and V2 also had similar characteristics with regard to the location (ca. 500 m east of the emission source), however, these maximum values occurred at different times and under different weather conditions. On the other hand, in the case of a grid with the resolution of 500 m (Variant V3), the maximum was obtained at a distance of ca. 1300 m, and, for a grid with the resolution of 1000 m (Variant V4), at a distance of ca. 1000 m from the source of emission (towards the north-east). Figures 4-6 present spatial distributions of maximum 1-h, maximum 24-h and average annual concentrations of NO\({}_{2}\) in the air obtained in the calculation area. Horizontal resolution of the calculation grid has some influence on the location of maximum values and the ability to identify local maxima.