# Prediction of Pollutant Emissions in Various Cases in Road Transport
## 3 Results
The authors then investigated the influence of the Euro standard and fuel type on emissions. The comparisons of NO\({}_{\chi}\) and PM2.5 emissions depending on Euro standards and fuel types are shown below in Figures 8 and 9. Figure 6: Comparison of CO\({}_{2}\) emissions from HDVs and buses depending on Euro standard and fuel type. Figure 7: Comparison of CO\({}_{2}\) emissions from L-category vehicles and buses depending on Euro standard and fuel type. In the cases of PCs and LDVs, the emissions of NO\({}_{\rm X}\) (Figures 8 and 9) and PM2.5 (Figures 10 and 11) from diesel oil were higher than those from biofuel. It is also worth noting that, similarly to CO\({}_{2}\) emissions (Figures 4-7), the emissions of NO\({}_{\rm X}\) and PM2.5 due to biofuel combustion were higher than those for gasoline, which was the opposite situation to diesel-fueled PCs and LDVs. Figure 8: Comparison of NOx emissions from PCs depending on Euro standard and fuel type. Figure 10: Comparison of NO\({}_{\rm X}\) emissions from HDVs and buses depending on Euro standard and fuel type. Figure 9: Comparison of NOx emissions from LDVs depending on Euro standard and fuel type. The PM2.5 emissions from diesel PCs and LDVs (Figures 12 and 13) were higher than those from biofuel. PM2.5 emission decreases with the increase of the Euro standard. Figure 11: Comparison of NO\({}_{\chi}\) emissions from L-category vehicles depending on Euro standard and fuel type. Figure 12: Comparison of PM2.5 emissions from PCs depending on Euro standard and fuel type. Figure 13: Comparison of PM2.5 emissions from LDVs depending on Euro standard and fuel type. In the cases of HDVs and buses, NO\({}_{\rm X}\) (Figure 10) and PM2.5 (Figure 14) emissions from biofuel were lower than those from diesel oil. The issue of PM2.5 emissions from Euro VI HDVs (Figure 14) demands further analysis. In the cases of NO\({}_{\rm X}\) and PM2.5 emissions from L-category vehicles (Figures 11 and 15), the lower emission from biofuel was observable only for the newest vehicles (Euro 5). As in the case of CO\({}_{2}\) emissions, NO\({}_{\rm X}\) and PM2.5 emissions decreased in line with the development of the Euro standards. Additionally, two scenarios were developed to determine the impact of the Euro 6 standards on CO\({}_{2}\), NO\({}_{\rm X}\) and PM2.5 emissions:  
* The first scenario focused on changing the current fleet by introducing Euro 6/VI vehicles, and then evaluating the benefit of fuel type;
* The second scenario focused on cities adding low-pollution zones (only Euro 6 vehicles and PHEVs, HEVs, and BEVs entering the city) and the effect of changing the fuel type on the CO\({}_{2}\), NO\({}_{\rm X}\), and PM2.5 emissions. The authors studied the impact of conversion of the entire fleet on CO\({}_{2}\), NOx and PM2.5 emissions. The first scenario assumed that all vehicles in Poland from the pre-Euro  
Figure 3:0 Comparison of PM2.5 emissions from HDVs and buses depending on Euro standard and fuel type. Figure 3:1 Comparison of PM2.5 emissions from L-category vehicles depending on Euro standard and fuel type. The simulation case in which all vehicles in Poland from pre-Euro to Euro 5 standard were converted to Euro 6 did not change the result in terms of CO2 emissions (Figure 16). This is because the vehicles used the same amount of fuel. However, emissions of NOx and PM2.5 decreased significantly. The second scenario focused on introducing low-pollution zones to cities and their impact on CO2, NOx, and PM2.5 emissions. It was assumed that only cars that met Euro 6 standards and PHEVs, HEVs, and BEVs could enter the cities. The results of the simulation are presented in two variants (for city traffic and all traffic, treated as urban, rural, and highway) and shown below in Figures 19-21. The case of the second scenario showed that the conversion impacted emissions. Emissions of CO\({}_{2}\), NO\({}_{\chi}\), and PM2.5 in cities were significantly reduced. The ban on entry to cities of cars other than those meeting the Euro 6/IV standard also impacted the total emissions.