Suitable corrugated filter grids (7, 7) are mounted on the suction intakes (6, 6) and are positioned with a downward inclination towards the conveyor (4) of the machine, their lower ends allowing drops to fall on to this conveyor. The suction intakes contain further removable filters (9, 9) and the lower ends of the said intakes are connected to a horizontal collector (10) which is positioned transversely under the conveyor of the machine and whose lower walls are inclined and converge towards a lower area in which is provided a tank (11) which collects all the paint precipitated by the filters located in the suction intakes and which is attached to the inner walls of the system by contact and by impact. An aperture (12) is provided in the intermediate part of one side of the said collector and is connected to a horizontal duct (13) of suitable section, which extends under the supply or discharge conveyor of the spraying machine and which has an extension at ninety degrees departing from the outline in plan view of this conveyor and connected to an ascending duct (14) connected by a bend to the suction intake of a centrifugal fan (16) whose outlet discharges into the atmosphere and which has a drainage duct (17) fitted on the lower part of its casing. The extension of this final part of the suction circuit also forms a trap for the recovery of further drops of paint carried by the air, and this circuit also has lower walls inclined downwards towards the said bottom tank (11) which collects the recovered paint by gravity.