What sorts of 02 and CO2 levels can humans tolerate?

I know that excess of either can cause problems, I'd like to know specific percentages for optimal health and the absolute limits.

I've tried to google it but i get swamped with global warming articles.

This is just for my own information.
Update: I thought i made it clear that i don't care about the (very dubious) effect of CO2 in global warming. I am also aware of the regular levels in the atmosphere. Oxygen does have an effect on humans; high concentrations cause respiratory (i want to know HOW high). thank you for the rough estimates of 5 and... show more I thought i made it clear that i don't care about the (very dubious) effect of CO2 in global warming. I am also aware of the regular levels in the atmosphere.
Oxygen does have an effect on humans; high concentrations cause respiratory (i want to know HOW high).
thank you for the rough estimates of 5 and 7%
BTW, Why do you call CO2 a 'crazy gas'? Do you realize no life could exist without it? Do you realize that it is a relatively stable gas and oxygen (comparatively) is a noxious, corrosive, toxic substance that did not occur in large proportions on earth for much of its history?
Read some REAL science
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