The production of both thermal and electrical power in pyro-gasification micro co-generative plants sized for small enterprises (sawmills, farms, cattle farms, etc.) is nowadays a growing trend. The electrical power is generated by an engine powered by the syngas produced through a pyro-gasification process; the nominal electric power of the considered plants is in between 30 and 90 kW. There are different types of plants currently available on the marketeither able to process only pure wood pellets either high quality virgin wood chips or raw and mixed bio-based materials, such as crops, secondary quality chips and other agricultural residues. In present framework our measurements are related to the third type, fed by secondary quality biomasses. The impact on the environment is due to the combustion of the syngas through the torch, switched on when the engine is off, due to the engineemissions, due to the tar and aromatic compounds intercepted by the filtering systems (according to the types either dry filters or water scrubbers) and finally due to the large amount of biochar resulting from the pyro-gasification process. In the present study the aero-dispersed pollutants measured are both dusts (in diametric classes from 1 to 10 ?m) and the concentration of few chemical compounds (such as sulfur dioxide, carbon monoxide, nitrogen dioxide and oxides). The concentration of atmospheric pollutants from the engine is related to the engine set-up and to the engine behavior and it is not only strictly related to the biomass quality. The main solid residue is the biochar, that can be a dangerous waste if stocked in unappropriated way but that can provide a beneficial impact in agriculture as well, when distributed and processed with the due techniques and concentrations.