When you are completley healthy and you have no problems whatsoever. Usually you reach this place in a place you love, a peacful moment, or meditating. Its quite a good place to be really....
I think you are asking about "standard" air. It is 80 degrees F. dry bulb, 67 degrees F. wet bulb. (about 50% relative humidity). 29.92 barometric pressure. its a specific case!In common, design...