I 'have seen masks for exercise before,
That lower oxygen or something,
But those masks always looked fancy skin tight with valves or something.
'Might be bad for one's brain,
'Might be some people have different breathing requirements than me.
'Might be bad to have lower oxygen than one is used to.
I say 'might, because some people live in high altitudes,
Seem to do fine,
. .
But of course they 'live in high altitudes,
Don't shift sudden all the time,
Altitude sickness is bad.
'Might be some people have different breathing requirements than me.
I found the masks 'annoying, but did not effect my breathing much.