Support structure for a vehicle dashboard

A support structure (12) for a dashboard assembly (10) for vehicles, comprising: a main transverse beam (20) with tubular shape forming a transverse air distribution conduit and provided with at least two end air outlets (30) and with at least one central air inlet (28), and at least one secondary transverse beam (26) with tubular shape, positioned below the main beam (20) and defining a conduit for distributing air towards the feet of at least one of the occupants of the front seats of the motor vehicle.