The objective of this study is to use a bio-sensor in order to assess environmental by metal trace elements (MTE) contamination in the Bourdj Bou Arreridj region, East of Algeria. The sampling of biological material from 32 locations was performed using a natural bioaccumulators represented by a lichenic species; Xanthoria parietina. Samples were taken and ten heavy metals (Fe, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb and Zn) were selected for analysis. The metal content recorded in various sampled sites were found greatly fluctuating and exceeded standard values with the exception of Pb at the Kseur and Ghilassa locations. The level of Fe was very high in all sampled locations with an average of (43184.4 ± 16373.7 mg/kg). This important accumulation of MTE in thalli was correlated to road and rail traffic as well as to industrial activities. These results show the tolerance of X. parietina to metallic stresses and therefore its effectiveness as a bio-sensor in the bio-monitoring programs assessing air quality.