Fire hazard in oxygen-enriched atmospheres at low barometric pressures.

Pilot studies are presently being carried out to determine the efficacy of raising the oxygen concentration in the room air of commercial and scientific facilities at altitudes of 4000-5500 m. This is a remarkably effective way of relieving hypoxia. For example, oxygen enrichment by only 5% (i.e., raising the oxygen concentration from 21 to 26%) reduces the equivalent altitude by 1500 m. However, concern has been expressed about the possibility of fire hazard. In this article, existing data from various sources have been analyzed to determine the burning rate of materials such as paper and cotton clothing at various altitudes when the PO2 in the air is increased to 110 mmHg to give an equivalent altitude of 3000 m. The analysis shows that in spite of the increase in oxygen concentration, the burning rate is much less than at sea level primarily because the PO2 is so much lower even with oxygen enrichment.