## 3 Results and Discussion
### Anthropogenic Sources' Contribution to Pollutant Emissions  
The average distribution of pollutants is reported in order to better understand the way of acting of the population. Figure 4 shows the day variation of pollutants in 2015, considering the mean value hour per hour and from winter to spring-autumn. The higher values can be traced in two times related to a greater flow of cars, when people go out in the morning and when they come back home in the evening (9.00 a.m., 7 p.m.). At night, there are lower values due to the turned-off heating systems (an Italian habit). In the winter, the values are even higher because of the heating systems.  
It is worth noticing that Frosinone shows, for most pollutant concentrations, higher values than Rome. It is peculiar because Rome is greater than Frosinone. These results are due to the vast presence of industrial plants in the area near Frosinone.  
Starting with the assumption that the pollutant concentration in winter is the combination of building heating systems and urban traffic while in spring and autumn the pollutant concentration is due only to urban traffic, in Tables 5-14 is reported the percentage repartition is calculated as the mean value of the typical day of Figure 4. So, for the type shown in Figure 4, it can be considered that the total pollutant emissions are the sum of heating systems and urban traffic. For this reason, it is possible to consider in Figure 4 the blue line has the total pollutant emissions and the red line the one related only to the urban traffic. Table 14 are reported the repartition of the urban traffic (UT) and heating systems (H) emissions that summed each other bring to 100% of the pollutant concentration. So taking into consideration the average difference from the blue line and the red line values of Figure 4 it is possible to show in Table 14 the results of that repartition. The analysis was done for all the cities of the Lazio region provinces.  
Considering the average values of all the pollutant concentrations and for all the cities, it is possible to notice that the emissions from urban traffic are the same as building heating systems. Higher emissions from urban traffic are referred to [NO\({}_{2}\)], [NO\({}_{\lambda}\)], [CO] and [PM\({}_{10}\)] with the average value for all the cities from 50.8% to 66.8%, while for building heating systems are [C\({}_{6}\)H\({}_{6}\)], [NO] and [PM\({}_{2.5}\)] with the average value for all the cities from 55.2% to 65.6%. In the cities of Rome and Viterbo, the percentages are significantly different and are higher of urban traffic for the most of pollutant concentration despite the other provinces. 58.7% and 60.9% of emissions are for urban traffic respectively for Rome and Viterbo. Opposite results are for Frosinone and Rieti in which there are more pollutant emissions from heating systems than from urban traffic. There is an average pollutant emission for urban traffic of 41.3% and 40.4% respectively for Frosinone and Rieti. Instead, for Latina, there is quite a balance from the two anthropogenic sources with values of 48.7% and 51.3% respectively for urban traffic and heating systems.  
The analysis of the contribution of the different anthropogenic sources to pollutant emissions highlights that, on a typical day of the year, there is quite a balance of levels due to urban traffic and heating systems. From this aspect, the policy strategy needs to have attention to both the pollutant sources paying more attention in the time of the time in which there are the most traffic or the more plants turned on, that is in the morning at about 9 A.M. and in the evening at about 7 A.M.