I know, but oxygen is harmfull and the amount of oxygen levels vary with elevation, so much so that even track records cannot be broken at sea level, or at places with too high of an elevation.

In 2 articles Referenced below my points are validated:

Oxygen can break down the very cells that make up our tissues and organs, our bones and even blood. It can damage DNA and critical enzymes (used for protein synthesis). It can injure and rigidify our cell membranes, making the movement of nutrients in and out of cells more harder. It could ruin our receptors for various hormones including testosterone (yep!), insulin, and thyroid.

This process of damaging the cell is similar to the way metal rusts and an apple core turns brown. The process is called cess oxidation or oxidative stress.

http://undergroundwellness.com/oxygen-is-killing-us/

Seems like an article in Nature (one of the most reputable journals in science) has the same idea, but they haven't taken my angle of elevation and oxygen levels in the atmosphere into consideration. Still want to do my study:

"Oxidative stress, is intricately connected to ageing and life span."

https://www.nature.com/articles/35041687