Sometime in the near future, a sizable population of humans has transported, through unspecified means, to a habitable super earth that has a much higher oxygen content than on Earth. Now, to the lay man that may sound like a good thing, the issue is however that too much oxygen can result in Oxygen Toxicity.
Fortunately, the unspecified means in which the humans have been transported to this world have also modified them to be able to survive in such an environment. With that said:
What possible modifications could be done to human physiology to live in a high oxygen world?
P.S. Ignore the super earth bit and other possible (fun) gasses that may be present. Those are for later
EDIT: For those wondering what the total atmospheric composition is, it's 70.1% Nitrogen, 24.9% Oxygen, 2% Argon, 1.2% Carbon Dioxide, 0.7% Ammonia, 0.01% Carbon Monoxide, 0.0001% Hydrogen Sulfide and trace amounts of other gases, mostly the noble gases, with pinch of Chlorine maintained through a small amount of metabolic process that also allow Ammonia and Hydrogen Sulfide. The atmosphere at sea level is also 1.55 atm.
Please note: the other gasses are irrelevant in this question, they may be getting their own questions and this iteration of the atmosphere may change as I flesh out my world even more.