Abstract: The present invention relates to a ventilating device for providing a zone (1) of clean air between the ventilating device and a workplace region (2), which ventilating device comprises air supply units (3) adapted to generating laminar air flows intended to constitute said clean air zone. The ventilating device comprises at least three air supply units (3) disposed in a closed pattern and air stop and guide units (4) which prevent or hinder air with bacteria-bearing and other pollutant particles which surrounds the clean air zone (1) from being drawn in between the air supply units and into the clean air zone.