## 3 Results and Discussion
### Enrichment Factors and Principal Component Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & **Factor 1** & **Factor 2** & **Factor 3** & **Factor 4** & **Factor 5** & **Factor 6** & **Factor 7** & **Factor 8** \\ \hline  & **Smoking** & **Combustion** & **Soil Dust** & **Vehicle** & **Road Dust** & **Abrasion** & **Soil** & **Vehicle** \\  & & & **Emissions** & & & **Surfaces** & & **sions** \\ \hline
**Eigenvalue** & 11.522 & **4.840** & 3.540 & 2.127 & 2.051 & 1.269 & 1.160 & 1.056 \\ \hline
**Cumulative \%** & 38.41 & **54.54** & 66.34 & 73.43 & 80.27 & 84.50 & 88.36 & 91.88 \\ \hline
**Acy** & 0.187 & **0.951** & \(-\)0.005 & \(-\)0.035 & 0.068 & \(-\)0.058 & \(-\)0.108 & 0.132 \\
**Ace** & \(-\)0.104 & **0.962** & 0.093 & \(-\)0.025 & \(-\)0.120 & 0.028 & 0.037 & 0.052 \\
**FI** & 0.088 & **0.973** & \(-\)0.026 & \(-\)0.063 & \(-\)0.030 & \(-\)0.060 & \(-\)0.087 & \(-\)0.065 \\
**PH** & 0.068 & **0.987** & \(-\)0.018 & \(-\)0.060 & 0.027 & \(-\)0.027 & \(-\)0.049 & \(-\)0.057 \\
**Ant** & 0.360 & **0.632** & \(-\)0.021 & \(-\)0.112 & 0.462 & 0.123 & \(-\)0.027 & \(-\)0.105 \\
**Flu** & **0.913** & 0.367 & 0.003 & \(-\)0.016 & 0.113 & 0.013 & 0.021 & \(-\)0.055 \\
**Pyr** & **0.975** & 0.115 & 0.071 & \(-\)0.007 & \(-\)0.027 & 0.035 & \(-\)0.047 & \(-\)0.007 \\
**Ba[A]** & **0.987** & 0.008 & 0.026 & 0.064 & 0.067 & 0.002 & 0.057 & 0.037 \\
**Chr** & **0.974** & 0.058 & 0.086 & \(-\)0.001 & \(-\)0.058 & 0.052 & 0.032 & \(-\)0.042 \\
**B[b]**F & **0.973** & 0.111 & 0.011 & \(-\)0.009 & 0.116 & 0.020 & 0.032 & 0.069 \\
**B[k]**F & **0.991** & 0.061 & 0.034 & 0.036 & 0.041 & 0.016 & 0.027 & 0.018 \\
**B[a]**P & **0.929** & \(-\)0.049 & \(-\)0.047 & 0.020 & 0.133 & 0.018 & 0.123 & 0.128 \\
**Ind** & **0.986** & 0.050 & 0.004 & 0.011 & 0.077 & \(-\)0.003 & 0.061 & 0.041 \\
**D[ah]A** & **0.971** & 0.033 & \(-\)0.070 & 0.004 & 0.033 & 0.053 & \(-\)0.006 & \(-\)0.023 \\
**B[ghi]**P & **0.940** & 0.018 & \(-\)0.078 & \(-\)0.039 & 0.145 & \(-\)0.052 & 0.191 & 0.029 \\
**Zn** & 0.261 & \(-\)0.091 & 0.310 & **0.613** & **0.563** & \(-\)0.159 & 0.050 & 0.216 \\
**Fe** & 0.152 & \(-\)0.158 & 0.032 & 0.048 & 0.133 & \(-\)0.080 & **0.910** & 0.015 \\
**Al** & \(-\)0.078 & \(-\)0.166 & **0.933** & \(-\)0.056 & 0.202 & 0.032 & \(-\)0.131 & 0.037 \\
**Hg** & **0.883** & \(-\)0.016 & 0.013 & \(-\)0.039 & \(-\)0.069 & 0.383 & 0.044 & \(-\)0.048 \\
**V** & 0.218 & \(-\)0.065 & **0.750** & 0.460 & 0.108 & 0.015 & 0.260 & 0.099 \\
**Cr** & 0.276 & 0.188 & 0.491 & 0.008 & 0.133 & **0.761** & \(-\)0.059 & 0.100 \\
**Mn** & 0.203 & \(-\)0.050 & 0.188 & 0.314 & \(-\)0.461 & \(-\)0.273 & 0.460 & \(-\)0.176 \\
**Ni** & **0.535** & 0.016 & \(-\)0.042 & 0.203 & 0.468 & \(-\)0.004 & **0.513** & \(-\)0.002 \\
**Cu** & 0.146 & 0.019 & 0.153 & \(-\)0.246 & **0.859** & \(-\)0.123 & 0.187 & \(-\)0.160 \\
**As** & \(-\)0.017 & \(-\)0.027 & 0.026 & **0.963** & \(-\)0.172 & \(-\)0.031 & \(-\)0.014 & \(-\)0.016 \\
**Se** & 0.203 & 0.298 & \(-\)0.127 & 0.112 & 0.049 & \(-\)0.299 & \(-\)0.225 & \(-\)0.635 \\
**Sr** & \(-\)0.077 & 0.263 & **0.897** & 0.177 & \(-\)0.138 & \(-\)0.066 & 0.083 & \(-\)0.120 \\
**Cd** & 0.123 & \(-\)0.158 & \(-\)0.195 & \(-\)0.033 & \(-\)0.145 & **0.893** & \(-\)0.103 & \(-\)0.039 \\
**Ba** & \(-\)0.184 & \(-\)0.276 & 0.357 & **0.691** & \(-\)0.156 & 0.070 & 0.259 & \(-\)0.174 \\
**Pb** & 0.198 & 0.154 & \(-\)0.074 & 0.022 & \(-\)0.044 & \(-\)0.117 & \(-\)0.130 & **0.802** \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Results of Principal Component Analysis (PCA). mainly natural origin. On factor 4, the main contribution of As and to a lesser extent of Ba and Zn implies the existence of sources related to vehicle traffic, while the presence of Cu and Zn on factor 5 is associated with the road dust resuspension [39]. Regarding factor 6, the significant contribution of Cd and Cr may be attributed to abrasion of plated surfaces (fragments of the coating of metal surfaces or galvanized paints).