The article shows the results of a research carried out on a landfill of automotive shredded residues, with the aim to assess the attenuation effects of a multilayer soil cover (clay, gravel and vegetable top soil layer) on the outwards migration of methane, VOCs and PAHs present in the biogas. As a consequence of the fixation and biodegradation phenomena the concentration of methane undergoes a reduction from 480,000 ppmv in the raw biogas to 22.51 ppmv in the outside air just above the soil cover. All VOCs, due to their good solubility in water and their bioavailability, have undergone a drastic reduction, while crossing the landfill cover, as much as to be detected in the outside air at a concentration lower than the limit of analytical detection. PAHs found in raw biogas have a chemical structure with four or five aromatic rings and a number of C atoms from 16 to 20 so that they have a very low water solubility and low biodegradability. They are present in biogas as particulate, so that the more significant removal mechanism appears the complex process of biogas filtration while crossing the multilayer cover. For them it stands out the remarkable reduction in the concentration of chrysene, from 48.5 ngNm-3 in the raw biogas to 3.0 ng Nm-3 in outdoor air. In any case, all the PAHs were detected in the outside air at concentrations lower than 5 ng Nm-3.