An air supply system (200, 300) for providing a clean air flow (250) in a room (1) is provided. The air supply system (200, 300) comprises a first air supply section (120) through which a first flow of clean air is supplied with a lower temperature than the temperature of the ambient air in the room (1), and a second air supply section (230) through which a second flow of clean air is supplied. The first air supply section (120) is arranged to form a gravitationally induced downward flow, whereas the second air supply section (230) is arranged to adjust the velocity (v1) of the second flow of clean air when entering the second air supply section (230) to a predetermined velocity (v2), and is adapted to direct the second flow of clean air downwards. A method (600) for providing a clean air flow in a room is further provided.
