No they don't. The partial pressure of oxygen reduces as the overall ambient pressure reduces. This gives an effective reduction in the percentage of oxygen available to burn.
Sea level 1bar 21% O2 79% Nitrogen Po2 is .21bar
18,000ft ambient pressure is .5 bar
Po2 is .1bar or 10%
Don't understand this, probably because I just don't understand the topic, but you seem to be saying that
0.21bar is 21% of 1bar, but 0.1bar is only 10% of 0.5bar
Do I have that right ?
FF
