Extinguishing fires with water usually causes a lot of damage to stock. In 2004, Emmi Frischprodukte from Ostermundigen in Switzerland decided that it would rather prevent fires than extinguish them. This is achieved by reducing the oxygen content in the warehouse from 21 to 13 to 17 per cent through the controlled addition of nitrogen into the air. In this atmosphere, it is practically impossible for a fire to start. The conditions in the warehouse are then similar to those encountered at an altitude of 3,000 meters. It is therefore safe for people to enter the warehouse. Messer has so far installed another six fire prevention systems in Switzerland.