Hypoxic air technology for fire prevention, also known as oxygen reduction system, is an active fire protection technique based on a permanent reduction of the oxygen concentration in the protected rooms. Unlike traditional fire suppression systems that usually extinguish fire after it is detected, hypoxic air is able to prevent fire. In a volume protected by hypoxic air, a normobaric hypoxic atmosphere is continuously retained: hypoxic means that the partial pressure of the oxygen is lower than at the sea level, normobaric means that the barometric pressure is equal to the barometric pressure at the sea level. Usually a 5% of oxygen molecules contained in the air is replaced by the same amount of nitrogen molecules: as a consequence a hypoxic atmosphere containing around 15 Vol% of oxygen and 85 Vol% of nitrogen is created. In a normobaric hypoxic environment, common materials cannot ignite or burn. Thus, considering the fire triangle, a fire cannot occur because of the lack of oxygen. The phenomena of fire prevention at higher oxygen concentration than the oxygen concentration required for extinguishing of established fire, has been observed and exploited for decades. Igor (Gary) Kotliar was the first to extensively explain the physics and to devise premixed hypoxic air for improved safety of applications for fire prevention, from 2001 onwards. Hypoxic air technology for fire prevention, also known as oxygen reduction system, is an active fire protection technique based on a permanent reduction of the oxygen concentration in the protected rooms. Unlike traditional fire suppression systems that usually extinguish fire after it is detected, hypoxic air is able to prevent fire. In a volume protected by hypoxic air, a normobaric hypoxic atmosphere is continuously retained: hypoxic means that the partial pressure of the oxygen is lower than at the sea level, normobaric means that the barometric pressure is equal to the barometric pressure at the sea level. Usually a 5% of oxygen molecules contained in the air is replaced by the same amount ofnitrogen molecules: as a consequence a hypoxic atmosphere containing around 15 Vol% of oxygen and 85 Vol% of nitrogen is created. In a normobaric hypoxic environment, common materials cannot ignite or burn. Thus, considering the fire triangle, a fire cannot occur because of the lack of oxygen. The phenomena of fire prevention at higher oxygen concentration than the oxygen concentration required for extinguishing of established fire, has been observed and exploited for decades. Igor (Gary) Kotliar was the first to extensively explain the physics and to devise premixed hypoxic air for improved safety of applications for fire prevention, from 2001 onwards