OXYGEN :

Earth Hydrosphere and Atmosphere oxygen content is
50%. Earthly surface contains 50% as oxydes and
silicates.

The ratio (O2/Air) remains the same up to 100km that
is to say 20.95% which means 120.10E13 tonnes.

However, Air pressure and consequently oxygen
pressure fastly decrease according to the altitude.

Beyond this altitude the oxygen concentration
decreases on behalf of ozone and atomic oxygen . The
ozone constitutes a protective layer at 25 km altitude
which absorbs sun irradiation (200-300nm) without
which human being would disappear. Nowadays, this
protective layer is threaten by chlorofluorocarbons

for short CFC .

Oxygen : A life symbol:

Atmospheric oxygen consumption is balanced by
vegetal-life chlorophylic biological cycle . Plants
release oxygen under sun light activation and absorb
carbon dioxide.

Oxygen water solubility is limited (10.1 mg/l at 0°C)
but is enough to insure the micro-organisms viability
which eliminate industrial wastes

thanks to biological cycle.

Human system takes up the oxygen lack in altitude by
increasing the cardiac rythm . After a stay of some
days there is an increase of red globules number
enabling oxygen blood carriage . It is admitted, that it
takes roughly two weeks for a young adult to
acclimate at the altitude of 4 to 5000 m.

OZONE DESTRUCTION :