Assertion: methane's concentration | /r/HasProperty | 23%
Facets:
value: by weight
type: OTHER
Source sentences:
text: The normal concentration of oxygen is 21% (by volume) or 23% (by weight) so this seems a rather small diminution, given that people can survive easily enough at altitudes where the atmospheric pressure is half normal, and I thought that the key issue was that for breathing to keep you alive you need the partial pressure of O2 in the air to be higher than the equilibrium partial pressure over a haemoglobin solution, thus the benefit of breathing pure oxygen at low pressure.