Biological process

Any process that results in a change in state or activity of a cell or an organism (in terms of movement, secretion, enzyme production, gene expression, etc.) as a result of a stimulus indicating lowered oxygen tension combined with low atmospheric pressure. Hypoxia is defined as a decline in O2 levels below normoxic levels of 20.8 - 20.95% and hypobaric is defined as atmospheric pressure below 0.74 atm (greater than 2,500 m above sea level).