Polluted air saturated with oil mist passes through a decantation chamber where, due to a strong reduction of flow speed, there is a pre-abatement. After this crucial step, polluted air is directed into a metal mesh filter in which the oily aerosol undergoes an effect of coalescence and the machining solid residue is separated from the gas flow. Once transformed the aerosol into drop, flow pass through a separator with vertical flow, then switch to corrugated filter cell, and finally flow through a rigid pocket filter efficiently F9. The air thus purified is conveyed to the chimney complying with the strictest environmental regulations.