The cabin air is pressurised by air from the jet engines.
Fresh air enters the cabin from above and is removed through openings at floor level.
Clinical investigations show that the recirculated air does not contain bacteria, viruses or other particles. Modern ventilation design prevents air in the cabin moving along the aircraft. In all aircraft the fresh air intake for each passenger is more than 10-20 times higher than actually needed. Recirculation decreases fuel consumption and makes the flight more economical.