Driving at altitude - oxygen chart

[sam2019]

Interesting. IMO and IME for a flatlander 15,000 feet is the critical level. short periods at 20,000 are possible (10 minutes about) but even at 12,000 long exposure (especially in the night when sleeping and breath is not deep) can lead to difficulties.

 

[sam2019]

• Oxygen Concentration Stays Same (Mostly): The percentage of oxygen in the air (around 21%) doesn't change, but the number of oxygen molecules you inhale decreases due to lower air pressure.
• Partial Pressure Drops: The key factor is the partial pressure of oxygen (pO2), which falls logarithmically with altitude, reducing how much oxygen your lungs can transfer to your blood.

 

[ham]

fortunately I live where the O2 molecules are packed fairly tightly

me wonders how ethanol laced fuels perform at altitude
as the ethanol does carry some O2 with it
would the lean condition from lets say E20
be offset by the rich condition brought on by altitude

 

[sam2019]

ethanol does carry some O2 with it

while technically true this Oxygen is bound in a hydroxyl group (OH group) and will not act as independent oxidizer