Filling tanks at altitude

[tbone1004]

Original post said filling at altitude and diving at sea level. So I should of made that more clear.

I was originally thinking it was less oxygen so I was referring to adjusting my dive computer to match the percentage. But that was corrected early in the conversation

Also agree always double check and run the math myself and not just ask. The reason for this whole post was to understand the why and best way to proceed.
Appreciate your help in understanding the info

yeah I saw that in the OP but was trying to cover all bases on there. Glad you got what you needed

 

[Bob from California]

Thanks, really appreciate the sharing of knowledge everyone

 

[lostsheep]

The OP does bring up an interesting question for me; surely at SOME altitude the composition of the atmosphere would change enough to warrant concern. I don’t know what that altitude is, and I doubt it’s in the troposphere so basically irrelevant for divers, but I’d be careful filling tanks in the stratosphere

 

[Wallowa]

The OP does bring up an interesting question for me; surely at SOME altitude the composition of the atmosphere would change enough to warrant concern. I don’t know what that altitude is, and I doubt it’s in the troposphere so basically irrelevant for divers, but I’d be careful filling tanks in the stratosphere

Damn Hoss....interesting question....here is what AI said ...way beyond my pay grade...note breathing ozone is not good...ozone is O3 so could be 1/3 fewer molecules? Nah, that is too easy.....

"The percentage of oxygen in the stratosphere is roughly the same as at sea level—about 21% of the atmosphere. However, the total amount of oxygen molecules decreases with altitude because the air becomes less dense.

In the stratosphere, ozone (O₃) plays a crucial role. It absorbs and protects us from the Sun’s harmful ultraviolet (UV) radiation. While oxygen levels remain proportionally similar, the higher concentration of ozone makes the air composition slightly different from the lower atmosphere."