Among various hazards related to long-duration space missions, fire accidents aboard spaceships or surface habitats can have the most devastating consequences. Self-sustained, long-duration human operations in deep space require a new paradigm for the fire-safety system design. Remarkably, all efforts were always focused on improvement of fire-suppression concepts and fire-inhibiting agents, presumably that a fire is inevitable and must be fought when started. It hasn't been considered that it might be possible to prevent fire from happening at all.

Since 1996 I have conducted an extensive study of the properties of normobaric hypoxic environments in research laboratory of Hypoxico Inc. in New York, using equipment of the Hypoxic Room System that I invented earlier, in 1993. I assumed, that breathable hypoxic air at normal atmospheric pressure would have ignition and combustion-related properties significantly different from those in hypobaric hypoxic or altitude environment air, having the same partial pressure of oxygen. Pilot experiments revealed that breathable normobaric hypoxic air, corresponding in partial pressure of oxygen to the air of moderate human-inhabited altitude of 7200' or 2200 m, actually provides complete ignition-suppressive and flame-eliminative effects and is perfectly suitable as a breathable fire-preventive atmosphere.

Experiments on ignition suppression and flame extinction were conducted in the Hypoxic Room System (manufactured by Hypoxico Inc., www.hypoxico.com ), which provides a normobaric environment of hypoxic, human-breathable air at room temperature. It was found that when oxygen concentration fell below 16.8%, no ignition of common combustible materials was possible. This concentration level was determined as the Hypoxic Threshold of Ignition Suppression. It is well known that the percent of oxygen content in the Earth atmosphere (20.94%) is constant at any given altitude within troposphere - from sea level up to the height of at least 10 km. Altitude has no significant inhibiting effect on ignition and combustion of inflammable materials. Even atop Mount Everest, where oxygen partial pressure is only 5.8 kPa, vs. 20 kPa at sea level, both ignition and combustion are possible . It is important to note that for human breathing the affinity of oxygen to hemoglobin depends only on its partial pressure, while the kinetic of combustion depends on the proportion of oxygen in the environmental gas mixture.

Mars Mission Planning and Engineering