### Current State of Knowledge on Particulate Matter Emissions from Road Transport
The national annual emissions of total particulate matter from traffic outside cities (45%) showed a similar value to that assessed for traffic in cities (44%). The lowest value of particulate matter emissions (12%) was observed in the case of highway traffic. Considerably high particulate matter emissions were observed in cities, which suggests a serious threat to health and the lives of many people, as these emissions affect highly populated urban areas. Figure 8 shows the national annual emissions of particulate matter from sources other than engine exhaust as a function of vehicle traffic patterns. The highest relative national annual emissions of particulate matter from sources other than engine exhaust gases were from vehicle traffic outside cities (nearly 50%), while in cities it was about 40% and on highways it was 10%. Figure 6: National annual emissions (E) of particulate matter from road transport. Figure 9 shows the national annual PM10 emissions as a function of vehicle traffic patterns. The highest relative national annual emission of PM10 was observed for vehicle traffic in cities (46%), while it was slightly lower outside cities (43%) and lowest on highways (11%). Once again, the health of residents in urban areas is threatened, as they are highly exposed to adverse effects of fine particles (PM10). Figure 10 shows the national annual emissions of PM10 from sources other than engine exhaust as a function of vehicle traffic patterns. The highest relative national annual emissions of PM10 from sources other than engine exhaust were observed for vehicle traffic outside cities (nearly 50%), whereas in cities these emissions constituted 42% and on highways they made up less than 10%. Figure 8: National annual emissions (E) of non-exhaust total suspended particles (PM-TSP-N-Exh) under different traffic conditions: urban (U), rural (R), highway (H) and total (T). Figure 7: National annual emissions (E) of total suspended particles (TSP-T) from road transport under different traffic conditions: urban (U), rural (R), highway (H) and total (T). Figure 11 shows the national annual emissions of PM2.5 depending on vehicle traffic patterns. From the research conducted it can be seen that the results were similar between PM2.5 and PM10 particles. The highest relative national annual emission of PM2.5 was observed in the case of traffic in cities (47%), while in traffic outside cities it was 41% and on highways it was only 12%. Figure 12 shows the national annual emissions of PM2.5 from sources other than engine exhaust gases depending on vehicle traffic patterns. From the conducted tests it can be seen that the relative results were similar between PM2.5 and PM10 particulate matter. The highest relative national annual emission of PM2.5 was for vehicle traffic outside cities (almost 50%), whereas in cities it was about 41% and on highways it was approximately 10%. Figure 10: National annual emissions (E) of non-exhaust particulate matter PM10 (PM10-N-Exh) under different traffic conditions: urban (U), rural (R), highway (H) and total (T). Figure 9: National annual emissions (E) of particulate matter PM10 (PM10-T) under different traffic conditions: urban (U), rural (R), highway (H) and total (T). Figure 13 shows the national annual soot (black carbon) emissions as a function of vehicle traffic patterns. The relative national annual soot emissions were highest in the case of urban traffic (51%), followed by non-urban traffic (36%), and at the lowest on highways (14%). Soot emissions are assumed to come only from engine exhaust. Figures 14 and 15 summarize the results of the study: the national annual emissions of particulate matter (Figure 14) and the relative national annual emissions of particulate matter (Figure 15) from road transport, depending on the vehicle traffic model. The average values of the relative national annual emissions of all particulate matter were similar for urban and non-urban traffic conditions (i.e., almost 44%).