Ventilation in layers and collecting system are two systems of ventilation, the first refers to air supply and the other refers to air extraction or air suction.
In Layers Ventilation we refer to a reduction of harmful gases and particulates, through additional supply of air blown in the work area.
While the primary purpose of the Collecting System is to extract these harmful materials, if possible directly from the point of origin (where's emitted) and to bring them into air extraction units and decontamination.