Serious consequences for public health result from exposure to harmful substances, particularly in the workplace. To what extent might exposure to petroleum and its byproducts impact human metabolism was the overarching issue that motivated this investigation. Using a sterile needle, 10 persons were picked from each of the following groups: the control group in Umuahia, the filling station attendants in the Choba district, and the motor mechanics and craftsmen departing from Mbodo Aluu. The hematological indices showed the following: PCV 24.50 (APH) to 44.60 (Control), HB(g/dl) 7.51 (APH) to 13.22 (Control), RBC(X1012/l) 2.45 (APH) to 6.13 (MAFL), WBC(X109/l) 5.63 (APH) to 37,000 (Control), Platelet(X109/l) 135 (MW) to 1416,000 (Control), MCV 4.01 (MW) to 6.70 (Control), MCH 2.37 (Control) to 3.72 (MW), and MCHC 0.307 (APH, MAFL, MW) to 0.308 (Control). There was little to no deviation from control values in the MCV, MCH, and MCHC results. Nevertheless, the experimental and control groups showed a significant disparity in PCV, HB, RBC, WBC, and platelet count at a confidence level of p<0.05. The results of this research suggest that polycyclic aromatic hydrocarbons may have a detrimental effect on the evaluated biochemical parameter's health.