[ghaff]

Chimborazo is not an 8K meter peak but it is the peak that's furthest from the center of the earth (because it's a fairly high 6K+ meter peak near the equator). Oxygen levels are, however, a function of height above sea level in a location--temperature is a function of many things--so Chimborazo in that respect is like other 6K meter peaks.

Proximity to outer space is an odd way to put it. I guess the atmosphere, to a first approximation, is also higher at the equatorial bulge.

[snowwrestler]

The atmosphere is thinner toward the poles. The partial pressure of oxygen at the summit of Denali in Alaska (6,000m) is about the same as at the summit of a 7,000m peak in the Himalayas.